#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;
}