Buggy python submission (verdict: Runtime Error):
import sys
N,M = map(int, input(). split())
s = [0,]*M
c = [0,]*M
ans =[10,]*N
for i in range(M):
    s[i], c[i] = map(int, input(). split())
    if ans[s[i]-1] != 10 and ans[s[i]-1] != c[i]:
        print(-1)
        sys.exit()
    else:
        ans[s[i]-1] = c[i]
if ans[0] == 0:
    print(-1)
    sys.exit()
elif ans[0] == 10:
    ans[0] = 1
    A = 0
    for j in range(N):
        if ans[j] == 10:
            ans[j] = 0
    for k in range(N):
        A += 10**(M-k)*ans[k] 
    print(A)
        
else:
    A = 0
    for j in range(N):
        if ans[j] == 10:
            ans[j] = 0
    for k in range(N):
        A += 10**(M-k)*ans[k] 
    print(A

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

s = [0,]*M
c = [0,]*M
ans =[10,]*N



for i in range(M):
    s[i], c[i] = map(int, input(). split())
    if ans[s[i]-1] != 10 and ans[s[i]-1] != c[i]:
        print(-1)
        sys.exit()
    else:
        ans[s[i]-1] = c[i]       
if N >= 2:
        
    A = 0        
    if ans[0] == 0:
        print(-1)
        sys.exit()
    elif ans[0] == 10:
        ans[0] = 1
        for j in range(N):
            if ans[j] == 10:
                ans[j] = 0
        for k in range(N):
            A += 10**(N-k-1)*ans[k] 
    
        print(A)
        
    else:
        for j in range(N):
            if ans[j] == 10:
                ans[j] = 0
        for k in range(N):
            A += 10**(N-k-1)*ans[k] 
        print(A)
else:
    A = 0
    if ans[0] == 0 or ans[0] == 10:
        print(0)
    else:
        print(ans[0])

Buggy python submission (verdict: Runtime Error):
import sys
N,M = map(int, input(). split())
s = [0,]*M
c = [0,]*M
ans =[10,]*M 
for i in range(M):
    s[i], c[i] = map(int, input(). split())
    if ans[s[i]-1] != 10 and ans[s[i]-1] != c[i]:
        print(-1)
        sys.exit()
    else:
        ans[s[i]-1] = c[i]

if ans[0] == 0:
    print(-1)
    sys.exit()
elif ans[0] == 10:
    ans[0] = 1
    A = 0
    for j in range(N):
        if ans[j] == 10:
            ans[j] = 0
    for k in range(N):
        A += 10**(M-(k+1))*ans[k] 
    print(A)
        
else:
    A = 0
    for j in range(N):
        if ans[j] == 10:
            ans[j] = 0
    for k in range(N):
        A += 10**(M-(k+1))*ans[k] 
    print(A)
    
    


    

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

s = [0,]*M
c = [0,]*M
ans =[10,]*N



for i in range(M):
    s[i], c[i] = map(int, input(). split())
    if ans[s[i]-1] != 10 and ans[s[i]-1] != c[i]:
        print(-1)
        sys.exit()
    else:
        ans[s[i]-1] = c[i]       
if N >= 2:
        
    A = 0        
    if ans[0] == 0:
        print(-1)
        sys.exit()
    elif ans[0] == 10:
        ans[0] = 1
        for j in range(N):
            if ans[j] == 10:
                ans[j] = 0
        for k in range(N):
            A += 10**(N-k-1)*ans[k] 
    
        print(A)
        
    else:
        for j in range(N):
            if ans[j] == 10:
                ans[j] = 0
        for k in range(N):
            A += 10**(N-k-1)*ans[k] 
        print(A)
else:
    A = 0
    if ans[0] == 0 or ans[0] == 10:
        print(0)
    else:
        print(ans[0])

Buggy python submission (verdict: Runtime Error):
import sys
N,M = map(int, input(). split())
s = [0,]*M
c = [0,]*M
ans =[10,]*M 
for i in range(M):
    s[i], c[i] = map(int, input(). split())
    if ans[s[i]-1] != 10 and ans[s[i]-1] != c[i]:
        print(-1)
        sys.exit()
    else:
        ans[s[i]-1] = c[i]

if ans[0] == 0:
    print(-1)
    sys.exit()
else:
    A = 0
    for j in range(N):
        if ans[j] == 10:
            ans[j] = 0
    for k in range(N):
        A += 10**(M-(k+1))*ans[k] 
    print(A)
    
    


    

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

s = [0,]*M
c = [0,]*M
ans =[10,]*N



for i in range(M):
    s[i], c[i] = map(int, input(). split())
    if ans[s[i]-1] != 10 and ans[s[i]-1] != c[i]:
        print(-1)
        sys.exit()
    else:
        ans[s[i]-1] = c[i]       
if N >= 2:
        
    A = 0        
    if ans[0] == 0:
        print(-1)
        sys.exit()
    elif ans[0] == 10:
        ans[0] = 1
        for j in range(N):
            if ans[j] == 10:
                ans[j] = 0
        for k in range(N):
            A += 10**(N-k-1)*ans[k] 
    
        print(A)
        
    else:
        for j in range(N):
            if ans[j] == 10:
                ans[j] = 0
        for k in range(N):
            A += 10**(N-k-1)*ans[k] 
        print(A)
else:
    A = 0
    if ans[0] == 0 or ans[0] == 10:
        print(0)
    else:
        print(ans[0])