#include <iostream>
#include <set>
#include <queue>
#include <vector>
#include <queue>
using namespace std;

int main() {

    queue<int> q;

    q.push(1);
    q.push(2);
    q.push(3);
    q.push(4);

    while(!q.empty()) {
        cout << q.front() << " ";
        q.pop();
    }


    return 0;
}