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);
	void push(int x);
	int pop();
	boolean isempty();
	boolean isfull();
};