#include<iostream>

template<typename T>
struct Node {
    T data;
    Node *next;
    Node(T data, Node *next) : data(data), next(next) {}
};

template<typename T>
class Stack {
    public:
        Stack() : top(nullptr), level(0), max_size(10) {}
        Stack(int max_size) : top(nullptr), level(0), max_size(max_size) {};
        void push(T data);
        T pop();
        void display();
        bool isEmpty() { return level == 0; }
        bool isFull() { return level == max_size; }
        int geLevel() { return level; }
        int getMaxSize() { return max_size; }

    private:
        Node<T> *top;
        int level, max_size;
};

template<typename T>
void Stack<T>::push(T data) {
    if(!isFull()) {
        Node<T> *newNode = new Node<T>(data, top);
        top = newNode;
        level++;
    } else {
        std::cerr << "stack overflow";
    }

}

template<typename T>
T Stack<T>::pop() {
    if(!isEmpty()) {
        Node<T> *temp = top;
        T data = temp->data;
        top = top->next;
        level--;
        delete temp;
        return data;
    }

    std::cerr << "stack underflow";

}

template<typename T>
void Stack<T>::display() {
    Node<T> *curr = top;
    while(curr != nullptr) {
        std::cout << curr->data << std::endl;
        curr = curr->next;
    }
}