/in/foo.cc: In function 'int main()':
/in/foo.cc:11:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i = 0; i < b.size(); i ++)
                    ^
/in/foo.cc:15:8: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   if(k > b.size()/2) cout << "Yes" << endl;
        ^