/in/foo.cc: In function 'int main()':
/in/foo.cc:10:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   10 |         for (int i=0;i<=s.size()-1;i++) str[i+1]=s[i];
      |                      ~^~~~~~~~~~~~
/in/foo.cc:11:23: 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 i=1;i<=s.size();i++)
      |                      ~^~~~~~~~~~
/in/foo.cc:13:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   13 |                 if (i==s.size()&&isalpha(str[i])) ls=str[i]+ls,cout<<ls;
      |                     ~^~~~~~~~~~