/in/foo.cc: In function 'int main()':
/in/foo.cc:17:30: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   17 |                 for(int i=0;i<s.size();i++)
      |                             ~^~~~~~~~~
/in/foo.cc:12:25: warning: unused variable 'b' [-Wunused-variable]
   12 |                 int a=0,b=s.size();
      |                         ^