// Stack abtract class
template <typename E> class Stack {
private:
void operator =(const Stack&) {} // Protect assignment
Stack(const Stack&) {} // Protect copy constructor
public:
Stack() {} // Default constructor
virtual ˜Stack() {} // Base destructor
// Reinitialize the stack. The user is responsible for
// reclaiming the storage used by the stack elements.
virtual void clear() = 0;
// Push an element onto the top of the stack.
// it: The element being pushed onto the stack.
virtual void push(const E& it) = 0;
// Remove the element at the top of the stack.
// Return: The element at the top of the stack.
virtual E pop() = 0;
// Return: A copy of the top element.
virtual const E& topValue() const = 0;
// Return: The number of elements in the stack.
virtual int length() const = 0;
};

WHILE(N)

​	PUSH(N%D)

​	N/=D

WHILE(!STACKEMPTY)

​	PRINT POP()