public class Stack {

private Node top;

public void push(int value) {

Node newNode = new Node(value);

newNode.next = top;

top = newNode;

System.out.println("Pushed " + value);

}

public boolean isEmpty() {

return top == null;

}

public int pop() {

int value = top.value;

top = top.next;

System.out.println("Popped " + value);

return value;

}

public int peek() {

return top.value;

}

@Override

public String toString() {

return "TOP -> " + ((top == null) ? "[EMPTY]" : top.toString());

}

public static void main(String[] args) {

// example usage

Stack stack = new Stack();

stack.push(1);

stack.push(2);

stack.push(3);

stack.push(4);

System.out.println(stack);

stack.pop();

stack.pop();

System.out.println(stack);

stack.push(5);

stack.push(6);

stack.push(7);

System.out.println(stack);

stack.pop();

stack.pop();

stack.pop();

stack.pop();

stack.pop();

System.out.println(stack);

}

}