class Stack2
{
private Queue<int> q1;
private Queue<int> q2;
public Stack2()
{
q1 = new Queue<int>();
q2 = new Queue<int>();
}
public void Push(int x)
{
q1.Enqueue(x);
}
public int Pop()
{
if (q1.Count == 0)
{
if (q2.Count == 0)
{
throw new Exception("为空");
}
else
{
while (q2.Count > 1)
{
q1.Enqueue(q2.Dequeue());
}
return q2.Deque