//mystk6.h -- CopyLeft by tsaiwn@csie.nctu.edu.tw
//implement a template class Stack using a vector
#include <vector>
using namespace std;
template <class T>
class MyStack {
   vector <T> x; 
public:
   void push(const T& y) {
      x.push_back(y);
   }
   T top( ) {
     return x.back( );
   }
   void pop( ) {
     x.pop_back( );
   }
   bool empty( ) { return x.begin() == x.end(); }
};