Queue by 2 Stacks

public class Queue<T> where T : class
{
    private Stack<T> input = new Stack<T>();
    private Stack<T> output = new Stack<T>();

    public void Enqueue(T t)
    {
        input.Push(t);
    }

    public T Dequeue()
    {
        if (output.Count == 0)
        {
            while (input.Count != 0)
            {
                output.Push(input.Pop());
            }
        }

        return output.Pop();
    }
}