/in/foo.cc: In function 'int main()':
/in/foo.cc:19:22: warning: array subscript has type 'char' [-Wchar-subscripts]
   19 |             num1[a[i]]++;
      |                      ^
/in/foo.cc:22:22: warning: array subscript has type 'char' [-Wchar-subscripts]
   22 |             num2[b[i]]++;
      |                      ^