#define TRUE 1
#define FALSE 0
#define MAX 100

typedef int BOOLEAN;

typedef struct {
	int A[MAX];
	int top;
}  STACK;

void clear(STACK *pS)
{
	pS->top = -1;
}

BOOLEAN isEmpty(STACK *pS)
{
	return (pS->top < 0);
}

BOOLEAN isFull(STACK *pS)
{
	return (pS->top >= MAX-1);
}

BOOLEAN pop(STACK *pS, int *px)
{
	if (isEmpty(pS))
		return FALSE;
	else {
		(*px) = pS->A[(pS->top)--];
		return TRUE;
	}
}

BOOLEAN push(int x, STACK *pS)
{
	if (isFull(pS))
		return FALSE;
	else {
		pS->A[++(pS->top)] = x;
		return TRUE;
	}
}