foo.cc: In function 'int main()':
foo.cc:13:26: warning: comparison of integer expressions of different signedness: 'll' {aka 'long long int'} and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   13 |                 for(i=0;i<s.size()-1;i++)
      |                         ~^~~~~~~~~~~
foo.cc:19:26: warning: comparison of integer expressions of different signedness: 'll' {aka 'long long int'} and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   19 |                 for(i=0;i<s.size()-1;i++)
      |                         ~^~~~~~~~~~~

[Hydro](https://hydro.ac)提供评测服务