/in/foo.cc:9:9: warning: #pragma once in main file
 #pragma once
         ^~~~
/in/foo.cc: In function 'bool check()':
/in/foo.cc:26:25: warning: array subscript has type 'char' [-Wchar-subscripts]
   int &c0 = to[str[0][i]],&c1 = to[str[1][i]],&c2 = to[str[2][i]];
                         ^
/in/foo.cc:26:45: warning: array subscript has type 'char' [-Wchar-subscripts]
   int &c0 = to[str[0][i]],&c1 = to[str[1][i]],&c2 = to[str[2][i]];
                                             ^
/in/foo.cc:26:65: warning: array subscript has type 'char' [-Wchar-subscripts]
   int &c0 = to[str[0][i]],&c1 = to[str[1][i]],&c2 = to[str[2][i]];
                                                                 ^
/in/foo.cc: In function 'int calc()':
/in/foo.cc:42:26: warning: array subscript has type 'char' [-Wchar-subscripts]
   op1 = (k + to[str[0][i]] + to[str[1][i]]);
                          ^
/in/foo.cc:42:42: warning: array subscript has type 'char' [-Wchar-subscripts]
   op1 = (k + to[str[0][i]] + to[str[1][i]]);
                                          ^
/in/foo.cc:44:29: warning: array subscript has type 'char' [-Wchar-subscripts]
   if(op1 % n != to[str[2][i]])
                             ^
/in/foo.cc:39:6: warning: unused variable 'sum' [-Wunused-variable]
  int sum = 0,k = 0,op1;
      ^~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:79:17: warning: array subscript has type 'char' [-Wchar-subscripts]
    cnt[str[i][j]]++;
                 ^
/in/foo.cc:83:20: warning: array subscript has type 'char' [-Wchar-subscripts]
    if(pos[str[i][j]] == -1)
                    ^
/in/foo.cc:84:18: warning: array subscript has type 'char' [-Wchar-subscripts]
     pos[str[i][j]] = j;
                  ^