/in/foo.cc: In function 'std::string del(std::string)':
/in/foo.cc:114:14: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  114 |     while (d < ans.size() && ans[d] == '0')
      |            ~~^~~~~~~~~~~~
/in/foo.cc:116:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  116 |     for (int i = d; i < ans.size(); i++) {
      |                     ~~^~~~~~~~~~~~