#include <iostream>
#include <stack>
#include <stdlib.h>
using namespace std;
//唉，模板都忘的差不多了，就写个整型的吧
class MyQueue{
private:
    stack<int> s1;
    stack<int> s2;
public:
    void enqueue(const int &n){
        s1.push(n);
    }
    int size() { return (s1.size()+s2.size()); }
    int dequeue(){
        if(s2.size()<=0){
            while(s1.size()>0){
                int& temp=s1.top();
                s1.pop();
                s2.push(temp);
            }
        }
        if(s2.size()==0){
            cout<<"Queue is empty"<<endl;
            exit(1);
        }
        int n=s2.top();
        s2.pop();
        return n;
    }
};
int main(){
    MyQueue q;
    for(int i=0;i<10;i++){
        q.enqueue(i);
    }
    cout<<"size="<<q.size()<<endl;
    cout<<q.dequeue()<<endl;
    cout<<"size="<<q.size()<<endl;
    q.enqueue(20);
    cout<<"size="<<q.size()<<endl;
    while(q.size()>0){
        cout<<"size="<<q.size()<<endl;
        cout<<q.dequeue()<<endl;
    }
    return 0;
}