/*
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 */

/**
 *
 * @author jiyou_000
 */
import java.util.Stack;

public class Queue <T>
{
    public Stack<T> s;

    public Queue()
    {
        s = new Stack<>();
    }

    public boolean empty()
    {
        return s.empty();
    }

    public void enqueue(T a)
    {
        if (s.empty())
        {
            s.push(a);
        }
        else
        {
            Stack<T> tmp = new Stack<>();
            while (!s.empty())
            {
                tmp.push(s.pop());
            }

            s.push(a);

            while (!tmp.empty())
            {
                s.push(tmp.pop());
            }
        }
    }

    public void dequeue() throws Exception
    {
        if (empty())
        {
            throw new Exception();
        }
        else
        {
            s.pop();
        }
    }
}