#include <stdio.h>

typedef struct node {
	int val;
	struct node *next;
} NODE;

typedef struct {
	NODE *head;
	int size;
} STACK;

/*
 * Creates an  empty stack
 */
void MakeEmptyStack(STACK *stack)
{
	printf("Stack Initialized!\n");
	stack->head = NULL;
	stack->size = 0;
}

/*
 * Return the boolean value for whether the stack is
 * empty or not
 */
int IsEmptyStack(STACK *stack)
{
	if (stack->head == NULL)
		printf("Stack Empty!\n");
	else
		printf("Stack has %d items!\n", stack->size);

	return (stack->head == NULL);
}


/*
 * Display head node information
 */
void top(STACK *stack)
{
	if (IsEmptyStack(stack))
		return;


	printf("\n===============================\n");
	printf("Printing Stack Head\n");
	printf("===============================\n");
	printf("Value: %d\n", (stack->head)->val);
	printf("Next Address: %d\n", (stack->head)->next);
	printf("===============================\n");
}


/*
 * Insert Value into head position
 */
void push(int value, STACK *stack)
{
	NODE *node;

	// allocate space
	node  = (NODE *) malloc (sizeof(NODE));

	// assign values
	node->val = value;
	node->next = stack->head;

	// point head to this node
	stack->head = node;

	// increase stack size
	(stack->size)++;
}

/*
 * Delete head node
 */
void pop(STACK *stack)
{
	NODE *p;

	if (IsEmptyStack(stack))
		return;

	printf("%d\n", (stack->head)->val);

	p = stack->head;

	stack->head = (stack->head)->next;
	(stack->size)--;

	free(p);
}


int main()
{
	STACK *stack;
	int i;

	stack = (STACK *)malloc(sizeof(STACK));

	MakeEmptyStack(stack);

	IsEmptyStack(stack);

	for(i=0; i<10; i++) {
		push(i, stack);
	}

	top(stack);

	IsEmptyStack(stack);

	for(i=0; i<10; i++) {
		pop(stack);
	}

}