foo.cc: In function 'int main()':
foo.cc:10:18: 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]
   10 |         for(i=0;i<=s.size();i++)
      |                 ~^~~~~~~~~~
foo.cc:17:43: 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]
   17 |                 if(s[i]=='+'||s[i]=='-'||i==s.size())
      |                                          ~^~~~~~~~~~

[Hydro](https://hydro.ac)提供评测服务