Brief, focused, stand-up meetings known as huddles have the potential to improve medical care by enabling collaborative and efficient information exchange and fostering a shared view of current clinical conditions.1 Huddles have been shown to minimize hierarchical barriers to care delivery, enhance frontline staff satisfaction, and improve clinical outcomes.2 In contrast to historically dominant provider-centric medical practice models, huddles operationalize medicine as a cooperative science: all team members (e.g., physicians, nurses, medical assistants, administrative staff, laboratory workers) work together for the patient’s good,3 promoting stronger teamwork and communication4 and situation awareness on the unit floor.1 This increased communication with and among members of the team may also lead to better understanding of the daily work of frontline staff, potentially a key to sustaining quality improvement.5

Ideally, huddles optimize participant engagement, last 10–15 min, focus only on essential patient and procedural information,1,6 and are held on a regular basis;7 in practice, however, huddles take many forms. Some may involve only the patient’s immediate clinical team, meeting as needed at the patient’s bedside.8 Others may involve all clinical and non-clinical staff and be scheduled for the start of each workday or other regular interval.9 Huddle structure may also vary, depending, in part, on the use of any facilitation strategies, scripts, or communication tools such as CUS (“I am concerned! I am uncomfortable! This is a safety issue!”)10 or SBAR (Situation-Background-Assessment-Recommendation).11 Yet despite understanding some of the myriad variations in huddle structures and processes, knowledge of huddle implementation and effectiveness at the frontlines of health care remains fragmented and is limited to particular settings. In a preliminary search for relevant reviews available through MEDLINE, the Cochrane Database of Systematic Reviews, and JBI Evidence Synthesis, we found three systematic reviews focusing on the use of huddles: one to promote patient safety in the perioperative setting2 and two focused on their use in inpatient settings.12,13 A more comprehensive understanding of huddle practices and characteristics has the potential to help clinicians and health care administrators across diverse settings understand how this process can help improve patient care.

In contrast to the prior, narrow systematic reviews on huddles in specific settings, this scoping review thus provides a comprehensive overview of the scope and volume of research on the broad category of clinical-setting huddles that involve frontline staff. In keeping with standard indications for conducting a scoping review,14 this review has the following purposes: to describe characteristics of such huddles (e.g., structures, processes), identify empirical support for the effectiveness of huddles for improving health care quality, and highlight knowledge gaps and opportunities for more detailed evidence syntheses and empirical research.


We performed this scoping review using the Joanna Briggs Institute’s established method for a scoping review15 and guidance from the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews (PRISMA-ScR).16 The final protocol was prospectively registered with the Open Science Framework17 on 18 January 2019 ( and published in the peer-reviewed literature.18

Scope of the Review

We used the PCC (Population, Concept, and Context) framework to define eligibility criteria.16 To be eligible for inclusion, articles had to (1) take place in any clinical or medical setting that provides health care patient services, including inpatient, outpatient, or residential settings; (2) include frontline staff members (i.e., employees with patient contact, including health care providers and non-clinical/administrative staff);19 (3) describe, investigate, or explore the huddling practice as a targeted intervention to improve processes and outcomes broadly related to quality of care (e.g., staff engagement and satisfaction, perceptions of safety culture, adverse drug events, patient length of stay); and (4) provide empirical data. Eligible study designs included qualitative studies; experimental and quasi-experimental studies (e.g., randomized or non-randomized controlled trials, before and after studies, interrupted time-series studies); analytic observational studies (e.g., prospective or retrospective cohort studies, case-control studies); and descriptive cross-sectional studies. Dissertations, gray literature, and conference proceedings that met inclusion criteria were also considered. We excluded study protocols; articles that described huddles as a platform through which other interventions were disseminated; articles that solely focused on adherence to a checklist (e.g., surgical safety checklist); simulation studies, and research summaries lacking original data.

Data Sources and Searches

To be as comprehensive as possible, we performed an initial limited search of PubMed and CINAHL Plus with Full Text, followed by an analysis of each identified article’s title, abstract, Medical Subject Headings (MeSH) terms, and keywords. For our full search, we used all resulting relevant MeSH terms and keywords to search the following databases: PubMed, EBSCOhost (including CINAHL Plus with Full Text, Dentistry & Oral Sciences Source, ERIC, Health Business Elite, Health Policy Reference Center, PsycArticles, PsycBooks, Psychology and Behavioral Sciences Collection, PsycINFO, Rehabilitation & Sports Medicine Source, Social Work Reference Center, and SocINDEX with Full Text), ProQuest (including the Family Health Database, Health & Medical Collection, Health Management Database, Nursing & Allied Health Database, Psychology Database, and PTSDpubs), and OvidSP. Appendix 1 lists the full search strategy used for PubMed, CINAHL Plus with Full Text, EBSCOhost, ProQuest, and OvidSP. We augmented the full database search by scanning the reference list of the Institute for Healthcare Improvement’s (IHI’s) white paper that guides health care practitioners in using daily huddles as part of a quality management system5 for additional articles that we then assessed. Studies published in English from inception to May 31, 2019, were considered for inclusion.

Study Selection

All articles identified during the full database and additional searches were uploaded into EndNote X8.2 (Clarivate Analytics, Philadelphia, PA, USA), and duplicates were removed. We conducted an initial screening for inclusion based on titles and abstracts. Two reviewers (C.B.P., C.W.H.) independently conducted the first screening of the abstracts based on the inclusion criteria to identify articles to include for further review. Disagreements on article inclusion were resolved by discussion or with input from two additional reviewers.

Following this, we reviewed the full text of those articles that met initial screening. Two independent reviewers assessed each article against the inclusion criteria, with disagreements resolved through discussion or with input from a third reviewer. Full-text articles that did not meet the inclusion criteria were excluded from the scoping review. Results of the search are presented in a PRISMA flow diagram (Fig. 1).16

Figure 1.
figure 1

PRISMA flow diagram.

Data Abstraction and Quality Assessment

Seven reviewers independently abstracted relevant data from each full-text article meeting all inclusion criteria. An Excel spreadsheet was used to collect data about, for example, clinical setting, study design, huddle purpose, participating staff, and indicators of huddle effectiveness. The data abstraction tool is available in Appendix 2. To summarize huddle purpose, we began with an adapted list of the four benefits of huddles as outlined by the IHI (engage, update, recognize, and identify)20 and added two additional ones based on our findings (plan, provide) (Table 1).

Table 1 Huddle Purpose and Outcome Measures (N=158 Articles)

Two secondary reviewers (C.B.P., C.W.H.) independently abstracted relevant data from all full-text articles to assess consistency with primary reviewers. As in the study selection process, disagreements between primary and secondary reviewers were resolved through team discussion or in consultation with a third reviewer. We did not perform formal assessments of methodological quality because a scoping review aims to provide an overview of the existing evidence, irrespective of quality.15,16 We did categorize studies by evidence quality (e.g., peer-reviewed, gray literature, presence of a control comparison group), however, to inform future research.

Role of the Funding Source

This work was supported by the US Department of Veterans Affairs, Veterans Health Administration, Office of Geriatrics and Extended Care, through the VA Community Living Centers’ Ongoing National Center for Enhancing Resources and Training. The funder had no role in study design or conduct, data collection, analysis or interpretation, or reporting.


We identified a total of 2,185 publications through electronic database searches and reference lists (Fig. 1). After removal of duplicate publications across databases (N=1,330) and exclusion after initial title and abstract review (N=535), we performed full-text review of 325 studies. Two researchers (a primary and secondary reviewer) independently reviewed each article, with 90% agreement between both reviewers prior to resolution through team discussion or in consultation with a third reviewer. One-hundred fifty-eight studies met inclusion criteria;1,6,8,9,11,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100,101,102,103,104,105,106,107,108,109,110,111,112,113,114,115,116,117,118,119,120,121,122,123,124,125,126,127,128,129,130,131,132,133,134,135,136,137,138,139,140,141,142,143,144,145,146,147,148,149,150,151,152,153,154,155,156,157,158,159,160,161,162,163,164,165,166,167,168,169,170,171,172,173 139 (88.0%) were peer-reviewed and 19 (12.0%) were gray literature. Details related to our broad objectives are summarized below. Select details on the included studies are available in Appendix 3.

Year and Location of Studies

The first study meeting eligibility criteria was published in 2004;11 the majority (71.5%; N=113) were published between 2014 and 2019.8,9,21,22,25,27,30,31,32,34,35,36,37,39,41,42,43,44,47,48,49,51,53,56,57,58,62,63,65,67,68,69,70,72,74,76,77,79,81,83,85,87,89,90,92,93,94,96,97,99,100,101,102,104,105,106,107,108,110,111,112,113,115,116,117,118,119,120,122,123,124,125,126,127,128,129,130,131,132,133,134,135,136,137,138,139,141,142,144,146,147,148,149,150,152,153,154,155,156,157,158,159,161,162,163,164,165,166,167,168,169,170,173 Seventy-four percent (N=117) were performed in the USA,1,6,8,9,11,21,23,25,27,28,30,33,34,35,37,38,39,40,42,43,44,46,47,48,49,50,51,52,53,55,56,57,58,59,60,61,62,64,65,69,71,72,74,76,77,78,84,85,86,87,88,89,91,93,96,97,98,99,100,101,102,104,106,107,109,112,114,115,116,117,118,119,120,121,122,123,124,125,126,128,129,130,131,132,135,136,137,138,139,140,141,142,143,144,145,146,147,149,150,151,152,153,155,156,158,159,160,161,164,165,166,167,168,169,170,172,173 13.9% (N=22) in the UK,22,26,29,31,36,41,54,63,67,70,75,79,83,92,94,105,110,111,113,133,154,162 8.9% (N=14) in Canada,24,32,45,68,73,80,82,90,103,108,127,134,157,171 and 3.2% elsewhere (the Netherlands [N=2],81,163 Thailand [N=1],95 Israel [N=1],66 and Australia [N=1]148).

Clinical Setting

A majority (30.4%; N=48) of all studies described implementation of huddle-based interventions throughout entire hospitals or health care systems.1,6,21,23,25,28,30,37,39,41,42,47,56,57,62,63,71,73,74,83,87,89,91,94,98,104,105,109,114,115,117,123,125,128,129,130,131,133,135,136,137,143,150,160,162,165,169,170 Specific unit-level clinical settings included the following: perioperative settings/operating room (15.2%; N=24),11,24,26,29,38,45,46,52,59,65,66,70,75,76,78,79,80,81,82,84,86,95,103,113 intensive care units (12.7%; N=20),33,44,50,61,77,88,96,108,110,112,121,124,138,140,151,152,159,163,171,172 inpatient medical or surgical departments (13.3%; N=21),35,49,51,54,60,67,85,92,99,100,101,111,116,118,141,147,154,155,157,168,173 long-term care facilities (6.3%; N=10),31,40,97,120,122,127,132,139,148,166 primary care (6.3%; N=10),43,55,58,64,68,69,93,142,149,164 emergency departments (5.1%; N=8),8,90,145,146,151,153,158,161 and labor and delivery (3.8%; N=6).53,72,119,126,156,167 Two percent or fewer studies were specific to each of the following settings: neurology and stroke (N=3),34,107,144 oncology (N=2),48,98 dental (N=2),22,36 behavioral health (N=2),27,139 pathology (N=1),32 radiology (N=1),9 cystic fibrosis (N=1),102 outpatient echocardiography laboratory (N=1),106 and brain and spinal cord rehabilitation (N=1).134

Study Design

Among peer-reviewed studies, 107 used quantitative methods only and 32 used qualitative or mixed methods. Among studies in the gray literature, 18 used quantitative and 1 used qualitative methods.

Only 9 studies (5.7%), all from the quantitative peer-reviewed literature, used a comparison group design.38,49,87,90,115,121,138,141,162 Nearly half of all studies (N=75) were analytic observational,1,23,26,28,31,34,37,41,46,47,48,50,51,55,58,59,60,61,67,71,72,74,75,76,77,78,79,80,83,84,86,89,91,94,96,97,99,101,106,107,109,110,111,112,115,117,119,123,125,128,129,130,132,133,134,137,140,142,143,146,147,148,150,153,157,158,159,160,161,163,166,167,168,170,172 34.2% (N=54) were experimental or quasi-experimental,8,11,27,29,32,33,35,38,42,43,45,49,51,52,53,56,65,70,73,81,85,87,90,92,95,102,103,104,105,108,113,114,116,118,120,121,122,124,125,126,131,135,136,138,139,141,144,149,152,155,156,162,165,173 and 9.5% (N=15) were descriptive cross-sectional.9,22,30,36,39,40,57,64,66,93,100,127,151,169,171 Twenty-one percent of studies (N=33) used qualitative methods,6,21,24,25,29,30,31,37,43,44,54,55,57,58,62,63,64,66,68,69,77,80,82,87,88,98,127,142,145,148,154,157,164 among which half (N=17) used mixed methods.29,30,31,37,43,57,58,64,66,68,77,80,87,127,142,148,157

Huddles were the sole intervention in 42.4% of studies (N=67)6,8,9,11,24,25,26,28,29,30,36,38,40,42,43,44,45,46,47,51,52,54,55,57,58,59,60,62,63,65,66,67,68,74,75,76,77,78,80,81,82,83,84,85,86,88,89,95,104,105,109,110,113,116,117,123,125,127,130,134,136,138,140,144,153,164,169 and part of a larger intervention bundle in 57.6% (N=91).1,21,22,23,27,31,32,33,34,35,37,39,41,48,49,50,53,56,61,64,69,70,71,72,73,79,87,90,91,92,93,94,96,97,98,99,100,101,102,103,106,107,108,111,112,114,115,118,119,120,121,122,124,126,128,129,131,132,133,135,137,139,141,142,143,145,146,147,148,149,150,151,152,154,155,156,157,158,159,160,161,162,163,165,166,167,168,170,171,172,173

Huddle Purpose

Studies used huddles for multiple purposes (Table 1). The majority (67.7%) of studies (N=107) described huddles as being used to engage team members in thinking and talking about their work and to improve communication, collaboration, and/or coordination.6,8,11,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100,101,102,103,104,105,106,107,108,109,110,111,112,113,114,115,116,117,118,119,120,121,122,123,124 Roughly equal numbers of studies described huddles used to identify issues requiring immediate attention or escalation to high-level management for resolution (27.2%; N=43);1,8,9,21,25,27,29,30,32,37,39,44,53,55,57,59,63,69,75,84,87,93,98,116,122,126,134,144,146,149,153,154,155,156,157,158,159,160,161,162,165,167,171 update team members about safety and quality issues that affect their work, including reviewing prior issues (24.1%; N=38);6,29,32,40,57,72,73,77,83,87,89,110,111,113,118,122,123,125,126,127,128,129,130,131,132,133,134,135,136,137,138,139,167,168,169,170,171,173 and plan for or improve processes for future work (22.8%; N=36).9,31,34,50,55,57,59,60,66,69,71,93,100,108,121,122,130,132,134,135,140,141,142,143,144,145,146,147,148,149,150,151,166,168,170,172 Fewer studies described huddles used to recognize work-related issues that may be addressed by training, coaching, or revising tools and methods (4.4%; N=7)40,57,62,89,112,152,169 or to provide a framework for running Plan-Do-Study-Act cycles (1.3%; N=2).163,164

Theories and Tools

More than one-third of the studies (37.3%; N=59) were based on a conceptual rationale,1,6,11,21,23,27,30,31,32,35,37,42,47,49,53,54,57,58,61,62,63,66,67,69,70,73,75,78,83,89,90,94,98,107,115,119,120,121,123,125,126,127,128,132,133,135,145,146,147,148,156,159,162,163,164,166,170,172,173 such as a theory (why the subject of interest will have an impact) and/or a framework or model (how a theory is operationalized).174 Among these studies, the most common were high reliability organizational principles (17.6%; N=9),1,6,63,69,70,123,125,128,135 crew resource management (17.6%; N=9),11,54,61,75,78,89,94,98,121 and Lean Six Sigma (15.7%; N=8).27,30,32,49,115,126,163,170

Only 7.6% of studies (N=12) mentioned organizing their huddles using existing tools or communication scripts (e.g., SBAR; Table 2);8,21,23,65,73,94,101,138,145,146,159,166 15.8% (N=25) developed and published their own huddling tools.27,29,36,42,45,46,49,50,51,56,60,68,78,80,87,89,96,98,104,112,130,134,136,141,153

Table 2 Common Tools Used to Communicate in or Monitor Frontline Staff Huddles

Participating Staff

In studies that identified huddle participants’ job categories (N=120), nurses were involved in 88.3% of the studies (N=106);1,6,8,9,11,21,24,25,26,28,29,30,34,35,36,37,38,39,40,41,42,43,44,45,46,49,50,51,53,54,55,56,57,58,59,60,62,63,65,66,68,69,70,71,72,73,75,77,78,79,80,81,83,84,85,86,87,88,89,91,95,96,98,99,100,103,104,110,111,112,113,114,117,119,120,121,122,123,125,127,129,130,133,136,138,140,142,143,144,145,146,147,148,149,150,152,153,155,157,158,159,160,162,164,165,173 physicians in 75.8% (N=91);6,9,11,24,26,28,29,30,32,35,36,38,39,40,41,42,43,44,45,46,49,50,51,53,54,55,56,57,58,59,62,63,65,66,68,69,70,71,72,73,75,78,79,80,81,83,84,85,86,87,91,94,95,96,98,99,100,101,103,104,108,109,110,111,112,113,114,117,118,119,121,122,123,134,136,140,141,142,145,146,149,152,153,155,157,158,160,162,164,165,172 members of ancillary services (e.g., social workers; pharmacists; technicians; case managers; respiratory, physical, or occupational therapists) in 50.8% (N=61);11,26,28,29,30,36,37,38,39,40,45,49,50,54,63,65,66,69,70,71,75,78,80,81,83,84,85,89,91,94,96,98,99,100,101,103,105,109,110,111,112,114,117,118,121,122,125,136,142,143,144,146,149,152,155,157,158,159,160,162,164 managers in 23.3% (N=28);1,6,9,21,25,27,30,32,34,40,44,57,63,69,74,88,89,98,117,123,126,136,143,150,162,164,169,172 and other frontline staff (e.g., clerical staff, environmental services) in 13.3% (N=16).9,30,32,37,55,58,63,68,89,94,98,125,136,162,164,169 Many huddles were interdisciplinary in nature, including participants from more than one job category. More than 24% of all studies (N=38) did not specify participants’ job categories. Three percent (N=5) of all studies explicitly included patients and/or their family members and peer supports.27,30,53,57,125

Nurses, usually charge nurses or nurse managers, facilitated the huddles in 40.0% of studies (N=20)1,28,29,30,43,44,57,60,85,88,89,112,125,129,130,136,138,147,149,150 where information on facilitator job category was included (N=52).1,9,21,22,28,29,30,33,35,40,43,44,47,51,54,55,57,59,60,68,69,71,83,84,85,87,88,89,98,99,100,108,111,112,117,123,125,127,129,130,135,136,138,145,147,149,150,162,164,169,170,171 Other huddle facilitators were attending physicians or medical directors (32.0%; N=16), 9,22,28,29,30,40,54,55,57,71,84,87,98,99,100,136 unspecified administrative leaders (26.9%; N=14),9,21,30,33,44,47,57,83,88,123,136,150,169,170 physician trainees (13.5%; N=7),1,35,51,55,100,108,117 unspecified members of the health care team (13.5%; N=7)57,59,68,69,127,145,162 or safety team (7.7%; N=4),47,135,136,171 and pharmacists (6.0%; N=3).111,136,164 In 67.1% (N=106) of all studies, information about huddle leaders was lacking.

Among studies that specified the number of huddle participants (N=31),1,8,31,42,45,53,55,58,62,65,68,71,72,82,87,91,100,104,118,127,138,140,142,144,145,148,153,158,163,165,169 a range of 2 to 20 frontline staff members attended huddles. Nearly 77% of the studies (N=121), however, did not specify the number of participants.

Huddles, when duration was specified, lasted anywhere between 2 and 30 min. Most of these huddles were held either once (41.1%; N=53)6,9,26,27,29,34,35,39,40,42,45,47,51,55,60,62,67,68,69,73,74,77,80,81,85,87,92,93,102,104,108,111,113,114,116,117,118,123,126,129,131,138,140,142,143,144,149,155,160,162,169,170,172 or twice (12.7%; N=20) daily,1,23,28,33,37,43,44,58,59,88,89,90,120,128,133,145,154,156,157,160 24.7% (N=39) before or after an event of interest (e.g., surgery, fall, activation of sepsis alarm),8,22,24,36,49,53,54,64,65,66,71,72,78,82,83,84,91,96,100,105,109,112,119,121,122,130,135,136,137,141,146,150,152,158,161,165,168,173 and 8.9% (N=14) on a weekly basis or more infrequently.30,31,32,66,110,127,132,134,147,148,163,164,166,171 Nearly 18% of studies (N=28) did not provide this level of detail when describing the huddles.

Effectiveness of Huddles

All 9 quantitative studies with a control comparison group reported statistically significant improvements associated with huddles.38,49,87,90,115,121,138,141,162 Of the 123 quantitative studies without a control comparison group, all but 2 reported improvements. Half (N=60) of these studies reported positive findings reaching statistical significance.1,27,29,32,33,35,39,41,45,46,51,52,56,58,61,65,71,72,75,78,79,80,81,84,85,91,94,99,101,102,103,104,106,109,112,113,116,117,118,119,122,125,129,130,134,135,139,142,143,144,146,148,149,152,155,156,157,163,165,173 All studies reported at least one outcome, with many reporting multiple process and clinical care outcomes. Of the 63.9% (N=101) studies measuring work and team process outcomes (Table 1), all but 1 reported that the huddle had a statistically significant positive impact on frontline staff.6,8,9,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,125,126,127,128,129,130,131,140,141,142,143,144,145,146,147,148,150,153,154,155,156,157 Of these, studies found evidence for improved efficiency, process-based functioning, and communication across clinical roles (64.4%; N=65);6,8,9,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,125,126,127,140,141,142,143,144,145,153,154,155 improved situational awareness and staff perceptions of safety and safety climate (44.6%; N=45); 6,8,11,26,30,31,35,36,37,40,45,46,47,53,55,56,57,60,62,63,67,68,69,71,73,74,75,76,77,78,79,80,81,82,83,84,85,86,128,129,145,146,147,153,156 increased staff satisfaction and engagement (29.7%; N=30);6,8,11,30,33,37,38,41,47,49,58,59,60,62,63,68,69,77,79,85,87,88,89,127,128,130,142,148,156,157 perceptions of a more supportive practice climate (26.7%; N=27); 6,8,9,11,28,30,40,43,47,49,50,57,58,62,66,67,68,69,71,79,84,85,90,91,127,154,156 and enhanced self-efficacy among frontline staff to implement evidence-based practices and/or improve care (20.8%; N=21).29,30,34,38,48,51,54,58,66,71,77,81,87,92,93,94,95,127,131,148,154 Only 2 qualitative studies (less than 2% of all studies) specifically assessed and reported on unintended negative consequences of the huddling practice, including added pressure on staff time and workload,22 exclusion of clinical trainees, and inadvertent reinforcement of medical hierarchies.24 We summarize the major findings on huddle team process outcomes in Fig. 2.

Figure 2
figure 2

Positive work and team process outcomes associated with frontline huddles (with percent of studies reporting each outcome; N=101). Studies could report more than one outcome; percent totals are over 100.

Seventy studies (44.3%) measured clinical care outcomes1,11,25,27,30,31,34,36,41,49,50,51,56,63,72,74,86,89,94,97,99,100,101,104,105,106,107,108,109,110,111,112,113,114,115,116,117,118,119,120,121,122,