foo.cc: In function ‘int main()’:
foo.cc:13:44: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::__cxx11::basic_string<char>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   13 |         for(int i=s.length()-t.length()+1;i<s.length();i++)
      |                                           ~^~~~~~~~~~~