/in/foo.cc: In function 'int main()':
/in/foo.cc:11:29: warning: array subscript has type 'char' [-Wchar-subscripts]
   11 |      cout << ch << " " << c[ch] << endl;
      |                             ^~
/in/foo.cc:16:7: warning: array subscript has type 'char' [-Wchar-subscripts]
   16 |     c[ch]++;
      |       ^~