/in/foo.cc: In function 'int main(int, char**, char**)':
/in/foo.cc:30:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for (int i = 0; i < s.size(); i++) {
                         ~~^~~~~~~~~~
/in/foo.cc:62:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < ans11.size(); i++) cout << ans11[i] << '\n';
                     ~~^~~~~~~~~~~~~~
/in/foo.cc:65:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < ans21.size(); i++) cout << ans21[i] << '\n';
                     ~~^~~~~~~~~~~~~~