/in/foo.cc: In function 'void solve()':
/in/foo.cc:18:14: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   18 |     while (i < xmin.size() && xmin[i] == '0') i++;
      |            ~~^~~~~~~~~~~~~
/in/foo.cc:19:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   19 |     if (i > 0 && i < xmin.size()) swap(xmin[0], xmin[i]);
      |                  ~~^~~~~~~~~~~~~