answer.code: In function ‘int main()’:
answer.code:16:39: error: could not convert ‘std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::substr(size_type, size_type) const [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>; size_type = long unsigned int](((std::__cxx11::basic_string<char>::size_type)j), ((std::__cxx11::basic_string<char>::size_type)m))’ from ‘std::__cxx11::basic_string<char>’ to ‘bool’
   16 |                         if(s[i].substr(j,m))
      |                            ~~~~~~~~~~~^~~~~
      |                                       |
      |                                       std::__cxx11::basic_string<char>