Buggy python submission (verdict: Runtime Error):
N,M= map(int,input().split())

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

L=[]
for i in range(N):
  L.append(1)
R=[1]
for i in range(N-1):
  R.append(0)
#print(R) 

for i in range(M):
  if R[x[i]-1]==1 and L[x[i]-1]==1:
    R[x[i]-1]=0
    L[x[i]-1]=0
    R[y[i]-1]=1
    L[y[i]-1]=L[y[i]-1]+1
  elif R[i]==1 and L[i]>=1:
    L[x[i]-1]=L[x[i]-1]-1
    R[y[i]-1]=1
    L[y[i]-1]=L[y[i]-1]+1
  elif R[x[i]-1]==0 and L[x[i]-1]>=1:
    L[x[i]-1]=L[x[i]-1]-1
    L[y[i]-1]=L[y[i]-1]+1
   
    
#print('R',R,'L',L)
print(R.count(1))


Fixed submission:
N,M= map(int,input().split())

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

L=[]
for i in range(N):
  L.append(1)
R=[1]
for i in range(N-1):
  R.append(0)
#print(R) 

#print('     ','R',R,'L',L) 
for i in range(M):
  if R[x[i]-1]==1 and L[x[i]-1]==1:
    R[x[i]-1]=0
    L[x[i]-1]=0
    R[y[i]-1]=1
    L[y[i]-1]=L[y[i]-1]+1
  elif R[x[i]-1]==1 and L[x[i]-1]>=1:
    L[x[i]-1]=L[x[i]-1]-1
    R[y[i]-1]=1
    L[y[i]-1]=L[y[i]-1]+1
  elif R[x[i]-1]==0 and L[x[i]-1]>=1:
    L[x[i]-1]=L[x[i]-1]-1
    L[y[i]-1]=L[y[i]-1]+1
  #print(i+1,x[i],y[i],'R',R,'L',L) 
    

print(R.count(1))

Buggy python submission (verdict: Runtime Error):
N,M= map(int,input().split())

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

L=[]
for i in range(N):
  L.append(1)
R=[1]
for i in range(N-1):
  R.append(0)
#print(R) 

for i in range(M):
  if R[x[i]-1]==1 and L[x[i]-1]==1:
    R[x[i]-1]=0
    L[x[i]-1]=0
    R[y[i]-1]=1
    L[y[i]-1]=L[y[i]-1]+1
  elif R[i]==1 and L[i]>=1:
    L[x[i]-1]=L[x[i]-1]-1
    R[y[i]-1]=1
    L[y[i]-1]=L[y[i]-1]+1
  elif R[x[i]-1]==0 and L[x[i]-1]>0:
    L[y[i]-1]=L[y[i]-1]+1
   
    
#print('R',R,'L',L)
print(R.count(1))


Fixed submission:
N,M= map(int,input().split())

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

L=[]
for i in range(N):
  L.append(1)
R=[1]
for i in range(N-1):
  R.append(0)
#print(R) 

#print('     ','R',R,'L',L) 
for i in range(M):
  if R[x[i]-1]==1 and L[x[i]-1]==1:
    R[x[i]-1]=0
    L[x[i]-1]=0
    R[y[i]-1]=1
    L[y[i]-1]=L[y[i]-1]+1
  elif R[x[i]-1]==1 and L[x[i]-1]>=1:
    L[x[i]-1]=L[x[i]-1]-1
    R[y[i]-1]=1
    L[y[i]-1]=L[y[i]-1]+1
  elif R[x[i]-1]==0 and L[x[i]-1]>=1:
    L[x[i]-1]=L[x[i]-1]-1
    L[y[i]-1]=L[y[i]-1]+1
  #print(i+1,x[i],y[i],'R',R,'L',L) 
    

print(R.count(1))

Buggy python submission (verdict: Runtime Error):
N,M= map(int,input().split())

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

L=[]
for i in range(N):
  L.append(1)
R=[1]
for i in range(N-1):
  R.append(0)
#print(R) 

for i in range(M):
  if R[i]==1 and L[i]==1:
    R[i]=0
    L[i]=0
    R[y[i]-1]=1
    L[y[i]-1]=L[y[i]-1]+1
  elif R[i]==1 and L[i]>0:
    L[i]=L[i]-1
    R[y[i]-1]=1
    L[y[i]-1]=L[y[i]-1]+1
  elif R[i]==0 and L[i]>0:
    L[y[i]-1]=L[y[i]-1]+1
   
    
#print(R,L)
print(R.count(1))


Fixed submission:
N,M= map(int,input().split())

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

L=[]
for i in range(N):
  L.append(1)
R=[1]
for i in range(N-1):
  R.append(0)
#print(R) 

#print('     ','R',R,'L',L) 
for i in range(M):
  if R[x[i]-1]==1 and L[x[i]-1]==1:
    R[x[i]-1]=0
    L[x[i]-1]=0
    R[y[i]-1]=1
    L[y[i]-1]=L[y[i]-1]+1
  elif R[x[i]-1]==1 and L[x[i]-1]>=1:
    L[x[i]-1]=L[x[i]-1]-1
    R[y[i]-1]=1
    L[y[i]-1]=L[y[i]-1]+1
  elif R[x[i]-1]==0 and L[x[i]-1]>=1:
    L[x[i]-1]=L[x[i]-1]-1
    L[y[i]-1]=L[y[i]-1]+1
  #print(i+1,x[i],y[i],'R',R,'L',L) 
    

print(R.count(1))

Buggy python submission (verdict: Runtime Error):
N,M= map(int,input().split())

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

L=[]
for i in range(N):
  L.append(1)
R=[1]
for i in range(N-1):
  R.append(0)
#print(R) 

for i in range(M):
  if R[i]==1 and L[i]==1:
    R[i]=0
    L[i]=0
    R[y[i]-1]=1
    L[y[i]-1]=L[y[i]-1]+1
  elif R[i]==1 and L[i]>1:
    L[i]=L[i]-1
    R[y[i]-1]=1
    L[y[i]-1]=L[y[i]-1]+1
  elif R[i]==0 and L[i]>0:
    L[y[i]-1]=L[y[i]-1]+1
   
    
#print(R,L)
print(R.count(1))


Fixed submission:
N,M= map(int,input().split())

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

L=[]
for i in range(N):
  L.append(1)
R=[1]
for i in range(N-1):
  R.append(0)
#print(R) 

#print('     ','R',R,'L',L) 
for i in range(M):
  if R[x[i]-1]==1 and L[x[i]-1]==1:
    R[x[i]-1]=0
    L[x[i]-1]=0
    R[y[i]-1]=1
    L[y[i]-1]=L[y[i]-1]+1
  elif R[x[i]-1]==1 and L[x[i]-1]>=1:
    L[x[i]-1]=L[x[i]-1]-1
    R[y[i]-1]=1
    L[y[i]-1]=L[y[i]-1]+1
  elif R[x[i]-1]==0 and L[x[i]-1]>=1:
    L[x[i]-1]=L[x[i]-1]-1
    L[y[i]-1]=L[y[i]-1]+1
  #print(i+1,x[i],y[i],'R',R,'L',L) 
    

print(R.count(1))