foo.cc: In function 'int main()':
foo.cc:15:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   15 |         for (int i = 0; i < str.size(); i++)
      |                         ~~^~~~~~~~~~~~
foo.cc:20:38: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   20 |                         for(int j=0;j<t.size();j++)
      |                                     ~^~~~~~~~~

[Hydro](https://hydro.ac)提供评测服务