foo.cc: In function ‘void output(std::string)’:
foo.cc:11:30: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::__cxx11::basic_string<char>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   11 |                 for(int j=0;j<s.size();j++)
      |                             ~^~~~~~~~~
foo.cc: In function ‘int main()’:
foo.cc:34:22: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::__cxx11::basic_string<char>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   34 |         for(int i=0;i<=n.size()+1;i++)
      |                     ~^~~~~~~~~~~~
foo.cc:36:21: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::__cxx11::basic_string<char>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   36 |                 if(i==n.size()+1)
      |                    ~^~~~~~~~~~~~