foo.cc: In function 'void solve()':
foo.cc:11:22: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   11 |         for(int i=0;i<s.size();i++){
      |                     ~^~~~~~~~~
foo.cc:13:30: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   13 |                 for(int j=i;j<s.size();j++){
      |                             ~^~~~~~~~~

[Hydro](https://hydro.ac)提供评测服务