/in/foo.cc: In function 'int main()':
/in/foo.cc:9:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
    9 |         for(;n<s.size();n++)
      |              ~^~~~~~~~~