/in/foo.cc: In function 'int main()':
/in/foo.cc:21:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   21 |    for (int n = 0; n < s[k].length(); n++)
      |                    ~~^~~~~~~~~~~~~~~
/in/foo.cc:25:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   25 |    for (int n = 0; n < s[k+1].length(); n++)
      |                    ~~^~~~~~~~~~~~~~~~~