foo.cc: In function ‘int kto10(std::string, int)’:
foo.cc:6:22: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::__cxx11::basic_string<char>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
    6 |         for(int i=0;i<n.size();i++)
      |                     ~^~~~~~~~~