/in/foo.cc: In function 'int main()':
/in/foo.cc:11:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int i = 0; i < l.length(); ++i) {
                     ^
/in/foo.cc:14:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   if ((l.length() + 1) / 2 <= num)cout << "Yes"<<endl;
                            ^