foo.cc: In function ‘int main()’:
foo.cc:16:18: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::__cxx11::basic_string<char>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   16 |     for(int i=0;i<str.size();i++){
      |                 ~^~~~~~~~~~~
foo.cc:33:22: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::__cxx11::basic_string<char>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   33 |         for(int j=0;j<num[i].size();j++)
      |                     ~^~~~~~~~~~~~~~