answer.code: In function ‘int main()’:
answer.code:44:27: error: cannot convert ‘std::string’ {aka ‘std::__cxx11::basic_string<char>’} to ‘int’
   44 |         if (has_substring(p, prime)) {
      |                           ^
      |                           |
      |                           std::string {aka std::__cxx11::basic_string<char>}
answer.code:24:24: note:   initializing argument 1 of ‘bool has_substring(int, int)’
   24 | bool has_substring(int p, int n) {
      |                    ~~~~^