deque

#pragma GCC optimize("O3")
#include <bits/stdc++.h>
using namespace std;

#define int long long
#define fastio ios_base::sync_with_stdio(0); cin.tie(0)
const int N = 1e6 + 5;

signed main()
{
    fastio;
    /*
    deque<int> q;
    q.size();
    q.empty();

    q.back();
    q.push_back();
    q.pop_back();

    q.front();
    q.push_front();
    q.pop_front();
    */
    deque<int> q;
    q.push_front(5);
    q.push_back(2);
    q.push_front(7);
    for(int i = 0; i < q.size(); i++){
        cout << q[i] << " ";
    }
    cout << '\n';
    // 7 5 2

}