//GenericLinkedListQueue
import java.util.LinkedList;

public class GenericLinkedListQueue<T> {
    private LinkedList<T> queueList;

    public GenericLinkedListQueue() {
        queueList = new LinkedList<>();
    }

    public void enqueue(T value) {
        queueList.addLast(value);
    }

    public T dequeue() {
        if (isEmpty()) {
            System.out.println("Queue is empty.");
            return null;
        } else {
            return queueList.removeFirst();
        }
    }

    public T peek() {
        if (isEmpty()) {
            System.out.println("Queue is empty.");
            return null;
        } else {
            return queueList.getFirst();
        }
    }

    public boolean isEmpty() {
        return queueList.isEmpty();
    }

    public int size() {
        return queueList.size();
    }
}
//Main
public class Main {
    public static void main(String[] args) {
        // Queue for Integers
        GenericLinkedListQueue<Integer> intQueue = new GenericLinkedListQueue<>();
        intQueue.enqueue(1);
        intQueue.enqueue(2);
        System.out.println(intQueue.dequeue());  // Output: 1
        System.out.println(intQueue.peek()); // Output: 2

        // Queue for Doubles
        GenericLinkedListQueue<Double> doubleQueue = new GenericLinkedListQueue<>();
        doubleQueue.enqueue(1.1);
        doubleQueue.enqueue(2.2);
        System.out.println(doubleQueue.dequeue());  // Output: 1.1
        System.out.println(doubleQueue.peek()); // Output: 2.2

        // Queue for Strings
        GenericLinkedListQueue<String> stringQueue = new GenericLinkedListQueue<>();
        stringQueue.enqueue("Hello");
        stringQueue.enqueue("World");
        System.out.println(stringQueue.dequeue());  // Output: Hello
        System.out.println(stringQueue.peek()); // Output: World
    }
}