public class IntegerStackLL { 

    IntegerLinkedList list;
    private int size;

    public IntegerStackLL() {
        list = new IntegerLinkedList();
        size = 0;
    }

    /** Pushes item onto the stack */
    public void push(int item) {
        Node node = new Node(item, null);
        list.insert(node);
        size++;
    }

    /** Pops off an item from the stack */
    public int pop() {
        if (isEmpty())
            throw new RuntimeException("Trying to pop an empty stack.");
        size--;
        return list.delete();
    }

    /** Returns the item at the top of the stack */
    public int top() {
        if (isEmpty())
            throw new RuntimeException("Trying to access an empty stack.");
        return list.peek();
    }

    /** Returns true iff the stack is empty. */
    public boolean isEmpty() {
        return size == 0;
    }

    /** Returns a string representation of the stack. */
    public String toString() {
        return list.toString();
    }

    public static void main(String[] args) { 
        int capacity = 15;
        IntegerStackLL is = new IntegerStackLL();

        // int n = is.pop();  this should cause an exception
        // int n = is.top();  this should cause an exception

        if (is.isEmpty())
            System.out.println("stack is empty");
        else
            System.out.println("stack is not empty");

        for (int i = 0; i < capacity; i++)
            is.push(i);

        is.push(capacity);

        System.out.println("stack before popping: " + is);
        System.out.println(is.pop());
        System.out.println("stack after popping: " + is);
        System.out.println("top of stack is: " + is.top());
    }
}