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

l = []

for i in range(m):
    ta,tb = map(int,input().split())
    l.append((ta-1,tb))
ans = [0]*n
l.sort()
if m ==0 and n==1:
    print(0)
    exit()
elif m ==0:
    print('1'+'0'*(n-1))
    exit()
elif n == 1:
    if len(set(l)) ==1:
        print(l[0][1])
    else:
        print(-1)
    exit()
elif l[0][1] == 0 and l[0][0]==0:
    print(-1)
    exit()
else:
    l = set(l)
    for i,j in l:
        if ans[i] ==0:
            ans[i] = j
        else:
            # print(i,j)
            print(-1)
            exit()
a = ''
for i in ans:
    a+=str(i)
if a[0]=='0':
    a='1'+a[1:]
print(a)

        
        


Fixed submission:

n,m = map(int,input().split())

l = []

for i in range(m):
    ta,tb = map(int,input().split())
    l.append((ta-1,tb))
ans = [0]*n
l.sort()
if m ==0 and n==1:
    print(0)
    exit()
elif m ==0:
    print('1'+'0'*(n-1))
    exit()
elif n == 1:
    if len(set(l)) ==1:
        print(l[0][1])
    else:
        print(-1)
    exit()
elif l[0][1] == 0 and l[0][0]==0:
    print(-1)
    exit()
else:
    l = set(l)
    for i,j in l:
        if ans[i] ==0:
            ans[i] = j
        else:
            # print(i,j)
            print(-1)
            exit()
a = ''
for i in ans:
    a+=str(i)
if a[0]=='0':
    a='1'+a[1:]
print(a)

Buggy python submission (verdict: Runtime Error):
dp = [[0]*3 for i in range(3)]
L = []
a = list(map(int,input().split()))
b = list(map(int,input().split()))
c = list(map(int,input().split()))
L = [a,b,c]
n = int(input())
l = []
for i in range(n):
    l.append(int(input()))

flag = 0 

for i in range(3):
    for j in range(3):
        if L[i][j] in l:
            dp[i][j] = 1
# dp = [[1,1,0],[0,1,0],[1,0,1]]
for i in range(3):
    if sum(dp[i]) ==3:
        flag = 1

for j in range(3):
    s = 0
    for i in range(3):
        s+= dp[i][j]
    if s == 3:
        flag = 1
s = 0
t = 0
for i in range(3):
    s+=  dp[i][i]
    t+= dp[i][2-i]
if s==3 or t == 3:
    flag = 1
    
if flag:
    print('Yes')
else:
    print('No')
# print(dp)

Fixed submission:

n,m = map(int,input().split())

l = []

for i in range(m):
    ta,tb = map(int,input().split())
    l.append((ta-1,tb))
ans = [0]*n
l.sort()
if m ==0 and n==1:
    print(0)
    exit()
elif m ==0:
    print('1'+'0'*(n-1))
    exit()
elif n == 1:
    if len(set(l)) ==1:
        print(l[0][1])
    else:
        print(-1)
    exit()
elif l[0][1] == 0 and l[0][0]==0:
    print(-1)
    exit()
else:
    l = set(l)
    for i,j in l:
        if ans[i] ==0:
            ans[i] = j
        else:
            # print(i,j)
            print(-1)
            exit()
a = ''
for i in ans:
    a+=str(i)
if a[0]=='0':
    a='1'+a[1:]
print(a)

Buggy python submission (verdict: Runtime Error):

n,m = map(int,input().split())

l = []

for i in range(m):
    ta,tb = map(int,input().split())
    l.append((ta-1,tb))
ans = [0]*n
l.sort()
if l[0][1] == 0:
    print(-1)
    exit()
else:
    for i,j in l:
        if ans[i] ==0 or ans[i] ==j:
            ans[i] = j
        else:
            # print(i,j)
            print(-1)
            exit()
a = ''
for i in ans:
    a+=str(i)
print(a)

        

Fixed submission:

n,m = map(int,input().split())

l = []

for i in range(m):
    ta,tb = map(int,input().split())
    l.append((ta-1,tb))
ans = [0]*n
l.sort()
if m ==0 and n==1:
    print(0)
    exit()
elif m ==0:
    print('1'+'0'*(n-1))
    exit()
elif n == 1:
    if len(set(l)) ==1:
        print(l[0][1])
    else:
        print(-1)
    exit()
elif l[0][1] == 0 and l[0][0]==0:
    print(-1)
    exit()
else:
    l = set(l)
    for i,j in l:
        if ans[i] ==0:
            ans[i] = j
        else:
            # print(i,j)
            print(-1)
            exit()
a = ''
for i in ans:
    a+=str(i)
if a[0]=='0':
    a='1'+a[1:]
print(a)