#include <iostream>
#include <queue>
using namespace std;
int main(void){
    queue<int> q;
    q.push(1);//add element
    q.push(2);
    q.push(3);
    while(!q.empty()){//queue is empty or not?
        cout << q.front()<<endl;//get first element
        q.pop();//removie element;
    }
    return 0;
}