/in/foo.cc: In function 'int main()':
/in/foo.cc:15:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i=0;i<s.size();++i)
                ^
/in/foo.cc:19:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   if(2*cnt>=s.size()) cout<<"Yes"<<endl;
           ^
/in/foo.cc:6:6: warning: unused variable 'n' [-Wunused-variable]
  int n;
      ^