#include <iostream>
#include <deque>
using namespace std;

int main() {

    deque<int> dq;

    dq.push_back(1);
    dq.push_back(2);
    dq.push_back(3);

    while(!dq.empty()) {
        cout << dq.front() << endl;
        dq.pop_front();
    }
    return 0;
}