/in/foo.cc:8:9: warning: #pragma once in main file
 #pragma once
         ^~~~
/in/foo.cc: In function 'bool check()':
/in/foo.cc:27:25: 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:27:45: 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:27:65: 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:64:25: warning: array subscript has type 'char' [-Wchar-subscripts]
   op1 = k + to[str[0][i]] + to[str[1][i]];
                         ^
/in/foo.cc:64:41: warning: array subscript has type 'char' [-Wchar-subscripts]
   op1 = k + to[str[0][i]] + to[str[1][i]];
                                         ^
/in/foo.cc:65:22: warning: array subscript has type 'char' [-Wchar-subscripts]
   if(k + to[str[0][i]] + to[str[1][i]] >= n)
                      ^
/in/foo.cc:65:38: warning: array subscript has type 'char' [-Wchar-subscripts]
   if(k + to[str[0][i]] + to[str[1][i]] >= n)
                                      ^
/in/foo.cc:73:32: warning: array subscript has type 'char' [-Wchar-subscripts]
   sum += abs(op1 - to[str[2][i]]);
                                ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:111:17: warning: array subscript has type 'char' [-Wchar-subscripts]
    cnt[str[i][j]]++;
                 ^