/in/foo.cc: In function 'long long unsigned int rnd()':
/in/foo.cc:14:22: error: 'isdigit' was not declared in this scope
     while(!isdigit(ch)){if(ch=='-')f=-1;ch=getchar();}
                      ^
/in/foo.cc:15:21: error: 'isdigit' was not declared in this scope
     while(isdigit(ch)){res=res*10+ch-'0';ch=getchar();}
                     ^
/in/foo.cc: In function 'long long unsigned int chk(long long unsigned int, long long unsigned int, long long unsigned int)':
/in/foo.cc:24:102: error: expected primary-expression before '/' token
     int ans1=a[x][y]-a[x-len][y]*fac2[len]-a[x][y-len]*fac1[len]+a[x-len][y-len]*fac1[len]*fac2[len];/
                                                                                                      ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:37:5: error: 'cin' was not declared in this scope
     cin>>n>>m;fac1[0]=fac2[0]=1;
     ^~~
/in/foo.cc:99:21: warning: this 'if' clause does not guard... [-Wmisleading-indentation]
                     if(mid)sum=mid;l=mid+1;
                     ^~
/in/foo.cc:99:36: note: ...this statement, but the latter is misleadingly indented as if it is guarded by the 'if'
                     if(mid)sum=mid;l=mid+1;
                                    ^
/in/foo.cc:115:21: warning: this 'if' clause does not guard... [-Wmisleading-indentation]
                     if(mid)sum=mid;l=mid+1;
                     ^~
/in/foo.cc:115:36: note: ...this statement, but the latter is misleadingly indented as if it is guarded by the 'if'
                     if(mid)sum=mid;l=mid+1;
                                    ^
/in/foo.cc:124:5: error: 'cout' was not declared in this scope
     cout<<ans+n*m;
     ^~~~