import java.util.ArrayList;

class GenericStack<T> {
    private ArrayList<T> stack;

    // Constructor
    public GenericStack() {
        stack = new ArrayList<>();
    }

    // Push method to add an element to the stack
    public void push(T value) {
        stack.add(value);
    }

    // Pop method to remove and return the top element of the stack
    public T pop() {
        if (isEmpty()) {
            throw new IllegalStateException("Stack is empty");
        }
        return stack.remove(stack.size() - 1);
    }

    // Peek method to return the top element without removing it
    public T peek() {
        if (isEmpty()) {
            throw new IllegalStateException("Stack is empty");
        }
        return stack.get(stack.size() - 1);
    }

    // Check if the stack is empty
    public boolean isEmpty() {
        return stack.isEmpty();
    }

    // Get the size of the stack
    public int size() {
        return stack.size();
    }
}

public class GenericStackDemo {
    public static void main(String[] args) {
        // Integer stack
        GenericStack<Integer> intStack = new GenericStack<>();
        intStack.push(1);
        intStack.push(2);
        intStack.push(3);
        System.out.println("Top of Integer stack: " + intStack.peek());
        System.out.println("Pop from Integer stack: " + intStack.pop());
        System.out.println("Size of Integer stack: " + intStack.size());

        // Double stack
        GenericStack<Double> doubleStack = new GenericStack<>();
        doubleStack.push(1.1);
        doubleStack.push(2.2);
        doubleStack.push(3.3);
        System.out.println("Top of Double stack: " + doubleStack.peek());
        System.out.println("Pop from Double stack: " + doubleStack.pop());
        System.out.println("Size of Double stack: " + doubleStack.size());

        // String stack
        GenericStack<String> stringStack = new GenericStack<>();
        stringStack.push("Hello");
        stringStack.push("World");
        System.out.println("Top of String stack: " + stringStack.peek());
        System.out.println("Pop from String stack: " + stringStack.pop());
        System.out.println("Size of String stack: " + stringStack.size());
    }
}