//myq6.h === queue using deque -- by tsaiwn@csie.nctu
#include <deque>
using namespace std;
template <class T>
class MyStack: deque<T> {
public:
   void push(const T& y) {
      MyStack<T>::push_back(y);
   }
   T top( ) {
     return MyStack<T>::front( );
   }
   void pop( ) {
     MyStack<T>::pop_front( );
   }
   bool empty( ) { 
     return MyStack<T>::begin() == MyStack<T>::end(); }
};