#include <stdio.h>

typedef int bool;

typedef int element;

#define MAX 20
#define EMPTY -1

struct stackinfo {
    element s[MAX];
    int top;
};

typedef struct stackinfo stack;

stack *create()
{
    stack *s = (stack *)malloc(sizeof(stack));
    s->top = EMPTY;
    return s;
}

bool isempty(stack *s)
{
    return s->top == EMPTY;
}
bool isfull(stack *s)
{
    return s->top == MAX-1;
}

void push(element data, stack *stk)
{
    stk->s[++stk->top] = data;
}
void pop(stack *stk)
{
    stk->top--;
}
element peek(stack *stk)
{
    return stk->s[stk->top];
}
void destroy(stack *s)
{
    free(s);
}

int main()
{
    stack *x;
    x = create();
    push(2, x);
    push(3, x);
    printf("%d\n", peek(x));
    pop(x);
    printf("%d\n", peek(x));
    pop(x);
    destroy(x);
}