foo.cc: In function 'int longest(std::string, int)':
foo.cc:15:9: warning: array subscript has type 'char' [-Wchar-subscripts]
   15 |   a[s[i]]++;
      |         ^
foo.cc:51:11: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   51 |  for(i=0;i<sleft.length();i++)
      |          ~^~~~~~~~~~~~~~~
foo.cc:52:16: warning: array subscript has type 'char' [-Wchar-subscripts]
   52 |   left[sleft[i]]++;
      |                ^
foo.cc:53:11: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   53 |  for(i=0;i<sright.length();i++)
      |          ~^~~~~~~~~~~~~~~~
foo.cc:54:18: warning: array subscript has type 'char' [-Wchar-subscripts]
   54 |   right[sright[i]]++;
      |                  ^

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