/in/foo.cc: In function 'int main()':
/in/foo.cc:23:9: warning: array subscript has type 'char' [-Wchar-subscripts]
   f[s[i]]++;
         ^
/in/foo.cc:24:12: warning: array subscript has type 'char' [-Wchar-subscripts]
   if(f[s[i]]>max)max=f[s[i]];
            ^
/in/foo.cc:24:28: warning: array subscript has type 'char' [-Wchar-subscripts]
   if(f[s[i]]>max)max=f[s[i]];
                            ^
/in/foo.cc:25:12: warning: array subscript has type 'char' [-Wchar-subscripts]
   if(f[s[i]]<min)min=f[s[i]];
            ^
/in/foo.cc:25:28: warning: array subscript has type 'char' [-Wchar-subscripts]
   if(f[s[i]]<min)min=f[s[i]];
                            ^