/in/foo.cc: In function 'int main()':
/in/foo.cc:11:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i=0;i<ss.size();++i){
                ^
/in/foo.cc:8:6: warning: unused variable 'n' [-Wunused-variable]
  int n;
      ^