STUPID_STACK

typedef struct stack
{
    int data;
    struct stack* prev;
}node_t;

node_t *push(node_t *stack, int data)
{
    node_t *elem = malloc(sizeof(node_t));
    elem -> prev = stack;
    elem -> data = data;

    return elem;
}

node_t *pop(node_t *stack, int *data)
{
    if (stack)
    {
        node_t *node = stack -> prev;
        *data = stack -> data;
        free(stack);
        return node;
    }

    return stack;
}

node_t *peek(node_t *stack, int *data)
{
    stack = pop(stack, data);
    stack = push(stack, *data);

    return stack;
}

void delete(node_t *stack)
{
    while (stack)
    {
        node_t *back = stack -> prev;
        free(stack);
        stack = back;
    }

    return;
}