/*  1  */
void stack_create(struct Stack * s)
{
    s->n = 0;
}

/*  2  */
struct Stack * stack_create(int size)
{
    struct Stack *s = malloc(sizeof(struct Stack));
    s->a = malloc(sizeof(int) * size);
    s->n = 0;
    s->size = size;
    return s;
}