/in/foo.cc: In function 'int main()':
/in/foo.cc:24:23: warning: comparison of integer expressions of different signedness: 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   24 |     while (ans.size() < n - m + 1)
      |            ~~~~~~~~~~~^~~~~~~~~~~