using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        var q = new Q();

        for(int i=0; i<=15000; i++) {

            q.Enqueue(i);

        }

        int n = 0;

        while(!q.IsEmpty())

            n = q.Dequeue();

        Console.WriteLine(n);

    }

}

​

public class Q

{

    private Stack<int> s1 = new Stack<int>();

    private Stack<int> s2 = new Stack<int>();

    public bool IsEmpty() { return s1.Count == 0; }

    public void Enqueue(int n)

    {

        s1.Push(n);

    }

    public int Dequeue()

    {

        Move(s1, s2);

        var ret = s2.Pop();

        Move(s2, s1);

        return ret;

    }

    private void Move(Stack<int> src, Stack<int> target) {

        while(src.Count > 0)

            target.Push(src.Pop());

    }

}