Accepted
/in/foo.cc: In function 'int main()':
/in/foo.cc:26:16: warning: array subscript has type 'char' [-Wchar-subscripts]
num[letter][0]++;
^
/in/foo.cc:30:14: warning: array subscript has type 'char' [-Wchar-subscripts]
num[letter][1]++;
^