Buggy python submission (verdict: Runtime Error):
import itertools as it

n,m=map(int,input().split())
ans=[]
for i in range(n):
    a,b=map(int,input().split())
    ans.append([a,b])
    ans.append([b,a])
  
a=0
for e in it.permutations(range(n)):
    #print(e)
    count=1
    if e[0]!=0:
        break
    
    for i in range(n-1):
        if [e[i]+1,e[i+1]+1] in ans:
            count*=1
        else:
            count*=0
            break
            
    a+=count
    
print(a)

Fixed submission:
import itertools as it
import sys

N, M = map(int, input().split())
if N==0 or M==0:
    print(0)
    sys.exit()
a=[]

for i in range(M):
    x,y=map(int,input().split())
    a.append([x,y])
    a.append([y,x])

ans=0
for e in it.permutations(range(N)):
    if e[0]!=0:
        break
        
    count=1
    for j in range(N-1):
        if [e[j]+1,e[j+1]+1] in a:
            count*=1
        else:
            count*=0
            break
            
    ans+=count

print(ans)

Buggy python submission (verdict: Runtime Error):
import itertools as it

n,m=map(int,input().split())
ans=[]
for i in range(n):
    a,b=map(int,input().split())
    ans.append([a,b])
    ans.append([b,a])
  
a=0
for e in it.permutations(range(n)):
    #print(e)
    count=1
    if e[0]!=0:
        break
    
    for i in range(len(e)-1):
        if [e[i]+1,e[i+1]+1] in ans:
            count*=1
        else:
            count*=0
            break
            
    a+=count
    
print(a)

Fixed submission:
import itertools as it
import sys

N, M = map(int, input().split())
if N==0 or M==0:
    print(0)
    sys.exit()
a=[]

for i in range(M):
    x,y=map(int,input().split())
    a.append([x,y])
    a.append([y,x])

ans=0
for e in it.permutations(range(N)):
    if e[0]!=0:
        break
        
    count=1
    for j in range(N-1):
        if [e[j]+1,e[j+1]+1] in a:
            count*=1
        else:
            count*=0
            break
            
    ans+=count

print(ans)

Buggy python submission (verdict: Runtime Error):
import itertools as it

n,m=map(int,input().split())
ans=[]
for i in range(n):
    a,b=map(int,input().split())
    ans.append([a,b])
    ans.append([b,a])
  
a=0
for e in it.permutations(range(n)):
    count=0
    if e[0]!=0:
        break
    
    for i in range(len(e)-1):
        if [e[i]+1,e[i+1]+1] in ans:
            count*=1
        else:
            count*=0
            break
            
    a+=count
    
print(a)

Fixed submission:
import itertools as it
import sys

N, M = map(int, input().split())
if N==0 or M==0:
    print(0)
    sys.exit()
a=[]

for i in range(M):
    x,y=map(int,input().split())
    a.append([x,y])
    a.append([y,x])

ans=0
for e in it.permutations(range(N)):
    if e[0]!=0:
        break
        
    count=1
    for j in range(N-1):
        if [e[j]+1,e[j+1]+1] in a:
            count*=1
        else:
            count*=0
            break
            
    ans+=count

print(ans)

Buggy python submission (verdict: Runtime Error):
import itertools as it

n,m=map(int,input().split())
ans=[]
for i in range(n):
    a,b=map(int,input().split())
    ans.append([a,b])
    ans.append([b,a])
  
a=0
for e in it.permutations(range(n)):
    count=0
    if e[0]!=0:
        break
    
    for i in range(len(e)-1):
        if [e[i]+1,e[i+1]+1] in ans:
            count=1
        else:
            count*=0
            
    a+=count
    
print(a)

Fixed submission:
import itertools as it
import sys

N, M = map(int, input().split())
if N==0 or M==0:
    print(0)
    sys.exit()
a=[]

for i in range(M):
    x,y=map(int,input().split())
    a.append([x,y])
    a.append([y,x])

ans=0
for e in it.permutations(range(N)):
    if e[0]!=0:
        break
        
    count=1
    for j in range(N-1):
        if [e[j]+1,e[j+1]+1] in a:
            count*=1
        else:
            count*=0
            break
            
    ans+=count

print(ans)

Buggy python submission (verdict: Runtime Error):
import itertools as it

n,m=map(int,input().split())
ans=[]
for i in range(n):
    a,b=map(int,input().split())
    ans.append([a,b])
    ans.append([b,a])
  
a=0
for e in it.permutations(range(n)):
    count=0
    if e[0]!=0:
        break
    
    for i in range(len(e)-1):
        if [e[i]+1,e[i+1]+1] in ans:
            count=1
        else:
            count=0
            
    a+=count
    
print(a)

Fixed submission:
import itertools as it
import sys

N, M = map(int, input().split())
if N==0 or M==0:
    print(0)
    sys.exit()
a=[]

for i in range(M):
    x,y=map(int,input().split())
    a.append([x,y])
    a.append([y,x])

ans=0
for e in it.permutations(range(N)):
    if e[0]!=0:
        break
        
    count=1
    for j in range(N-1):
        if [e[j]+1,e[j+1]+1] in a:
            count*=1
        else:
            count*=0
            break
            
    ans+=count

print(ans)

Buggy python submission (verdict: Runtime Error):
import itertools as it

n,m=map(int,input().split())
ans=[]
for i in range(n):
    a,b=map(int,input().split())
    ans.append([a,b])
    ans.append([b,a])
  

for e in it.permutations(range(n)):
    count,a=0,0
    if e[0]!=0:
        break
    
    for i in range(len(e)-1):
        if [e[i]+1,e[i+1]+1] in ans:
            count=1
        else:
            count=0
            
    a+=count
    
print(a)

Fixed submission:
import itertools as it
import sys

N, M = map(int, input().split())
if N==0 or M==0:
    print(0)
    sys.exit()
a=[]

for i in range(M):
    x,y=map(int,input().split())
    a.append([x,y])
    a.append([y,x])

ans=0
for e in it.permutations(range(N)):
    if e[0]!=0:
        break
        
    count=1
    for j in range(N-1):
        if [e[j]+1,e[j+1]+1] in a:
            count*=1
        else:
            count*=0
            break
            
    ans+=count

print(ans)

Buggy python submission (verdict: Runtime Error):
import itertools as it

n,m=map(int,input().split())
ans=[]
for i in range(n):
    a,b=map(int,input().split())
    ans.append([a,b])
    ans.append([b,a])
  
count,a=0,0
for e in it.permutations(range(n)):
    if e[0]!=0:
        break
    
    for i in range(len(e)-1):
        if [e[i]+1,e[i+1]+1] in ans:
            count=1
        else:
            count=0
            
    a+=count
    
print(a)
        

Fixed submission:
import itertools as it
import sys

N, M = map(int, input().split())
if N==0 or M==0:
    print(0)
    sys.exit()
a=[]

for i in range(M):
    x,y=map(int,input().split())
    a.append([x,y])
    a.append([y,x])

ans=0
for e in it.permutations(range(N)):
    if e[0]!=0:
        break
        
    count=1
    for j in range(N-1):
        if [e[j]+1,e[j+1]+1] in a:
            count*=1
        else:
            count*=0
            break
            
    ans+=count

print(ans)

Buggy python submission (verdict: Runtime Error):
import itertools as it
import sys

N, M = map(int, input().split())
if N==0 or M==0:
    print(0)
    sys.exit()
a=[]

for i in range(N):
    x,y=map(int,input().split())
    a.append([x,y])
    a.append([y,x])

ans=0
for e in it.permutations(range(N)):
    if e[0]!=0:
        break
        
    count=1
    for j in range(N-1):
        if [e[j]+1,e[j+1]+1] in a:
            count*=1
        else:
            count*=0
            break
            
    ans+=count

print(ans)

Fixed submission:
import itertools as it
import sys

N, M = map(int, input().split())
if N==0 or M==0:
    print(0)
    sys.exit()
a=[]

for i in range(M):
    x,y=map(int,input().split())
    a.append([x,y])
    a.append([y,x])

ans=0
for e in it.permutations(range(N)):
    if e[0]!=0:
        break
        
    count=1
    for j in range(N-1):
        if [e[j]+1,e[j+1]+1] in a:
            count*=1
        else:
            count*=0
            break
            
    ans+=count

print(ans)

Buggy python submission (verdict: Runtime Error):
import itertools as it
import sys

N, M = map(int, input().split())
if N==0 or M==0:
    print(0)
    sys.exit()
a=[]

for i in range(N):
    x,y=map(int,input().split())
    a.append([x,y])
    a.append([y,x])

ans=0
for e in it.permutations(range(N)):
    if e[0]!=0:
        break
        
    count=1
    for j in range(M-1):
        if [e[j]+1,e[j+1]+1] in a:
            count*=1
        else:
            count*=0
            break
            
    ans+=count

print(ans)

Fixed submission:
import itertools as it
import sys

N, M = map(int, input().split())
if N==0 or M==0:
    print(0)
    sys.exit()
a=[]

for i in range(M):
    x,y=map(int,input().split())
    a.append([x,y])
    a.append([y,x])

ans=0
for e in it.permutations(range(N)):
    if e[0]!=0:
        break
        
    count=1
    for j in range(N-1):
        if [e[j]+1,e[j+1]+1] in a:
            count*=1
        else:
            count*=0
            break
            
    ans+=count

print(ans)

Buggy python submission (verdict: Runtime Error):
import itertools as it

N, M = map(int, input().split())
a=[]

for i in range(N):
    x,y=map(int,input().split())
    a.append([x,y])
    a.append([y,x])

ans=0
for e in it.permutations(range(N)):
    if e[0]!=0:
        break
        
    count=1
    for j in range(M-1):
        if [e[j]+1,e[j+1]+1] in a:
            count*=1
        else:
            count*=0
            break
            
    ans+=count

print(ans)


Fixed submission:
import itertools as it
import sys

N, M = map(int, input().split())
if N==0 or M==0:
    print(0)
    sys.exit()
a=[]

for i in range(M):
    x,y=map(int,input().split())
    a.append([x,y])
    a.append([y,x])

ans=0
for e in it.permutations(range(N)):
    if e[0]!=0:
        break
        
    count=1
    for j in range(N-1):
        if [e[j]+1,e[j+1]+1] in a:
            count*=1
        else:
            count*=0
            break
            
    ans+=count

print(ans)