typedef enum {false, true} boolean;

class int_stack {
	class node {
	public:
		int data;
		node* next;
	};
	node* new_node(int d, node* n);
	node* top;
public:
	// Note that the stack is implicit
	void init(int nitems = 100) { top = 0; }
	void push(int x) { top = new_node(x, top); }
	int pop();
	boolean isempty() { return( top == 0 ); }
	boolean isfull() { return( 0 ); }
};