View Compilation Error

0_0_15540794_22052.cpp: In function 'void Solve()':
0_0_15540794_22052.cpp:104:11: error: 'i' was not declared in this scope
         f[i]=i;
           ^
0_0_15540794_22052.cpp:140:21: error: 'ans' was not declared in this scope
                     ans=(ans*ret)%mod;//????????????????????????????                    for(int a=0; a<len; a++)
                     ^
0_0_15540794_22052.cpp:141:32: error: 'a' was not declared in this scope
                         f[V[i][a]]=i;
                                ^
0_0_15540794_22052.cpp:171:29: error: 'ans' was not declared in this scope
     printf("%I64d\n",flag?0:ans%mod);
                             ^