import java.util.*;

public class MyQueueArray implements MyQueue {

    private Object[] queue;
    private int size; // size of the queue
    private int top;  // for next insertion
    private int base; // for next removal

    public MyQueueArray() {
        queue = new Object[1];
        size = top = base = 0; 
    }
  
    public boolean isEmpty() {
        return size == 0;
    }

    public void enqueue(Object item) {
        if (size == queue.length) {
            // expand the queue
            Object[] newQueue = new Object[2*queue.length];
            System.arraycopy(queue, base, newQueue, 0, size-base);
            System.arraycopy(queue, 0, newQueue, size-base, base);
            queue = newQueue;
            base = 0;
            top = size;
        }
        queue[top++] = item;
        if (top == queue.length) {
            top = 0;
        }
        ++size;
    }

    public Object dequeue() {
        if (size == 0) {
            throw new NoSuchElementException();
        } else {
            Object item = queue[base++];
            if (base == queue.length) {
                base = 0;
            }
            --size;
            return item; 
        }
    }

    public Enumeration elements() {
        // put your code here
    }
  
}