foo.cc: In function 'int Count(std::string)':
foo.cc:5:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
    5 |     for(int i=0;i<s.size();i++){
      |                 ~^~~~~~~~~