template <class T>
struct Node
{
    T data;
    Node<T> *next;
};
template <class T>
class LinkStack
{
private:
    Node<T> *top;

public:
    LinkStack() { top = NULL; }
    ~LinkStack();
    void push(T x);
    T pop();
    T GetTop();
    bool Empty() { return top == nullptr; }
};

template <class T>
LinkStack<T>::~LinkStack()
{
    while (top)
    {
        Node<T> *p = top;
        top = top->next;
        delete p;
    }
}
template <class T>
void LinkStack<T>::push(T x)
{
    Node<T> *now = new Node<T>;
    now->data = x;
    now->next = top;
    top = now;
}
template <class T>
T LinkStack<T>::pop()
{
    if (Empty())
        throw "栈空";
    T x = top->data;
    Node<T> *tmp = top;
    top = top->next;
    delete tmp;
    return x;
}
template <class T>
T LinkStack<T>::GetTop()
{
    if (Empty())
        throw "栈空";
    return top->data;
}