#include<bits/stdc++.h>
#define pb push_back
#define int long long
#define all(x) (x).begin(), (x).end()
using namespace std;

const int N = 5e5 + 5;

int a[N], n;
mt19937 gen;

struct node {
    int key, val, mx, prior;
    node *l, *r;
    node(int k, int v) {
        key = k;
        mx = val = v;
        prior = gen();
        l = r = 0;
    }
};

using tnode = node*;

int mx(tnode t) {
    return (t ? t -> mx : -1);
}

void recalc(tnode &t) {
    if (t)
        t -> mx = max({t -> val, mx(t -> l), mx(t -> r)});
}

void merge(tnode &t, tnode l, tnode r) {
    if (!l)
        return void(t = r);
    if (!r)
        return void(t = l);
    if (l -> prior > r -> prior)
        merge(l -> r, l -> r, r), t = l;
    else
        merge(r -> l, l, r -> l), t = r;
    recalc(t);
}

void split(tnode &t, tnode l, tnode r, int key) { // <=
    if (!t)
        return void(l = r = 0);
    if (t -> key <= key)
        split(t -> r, t -> r, r, key), l = t;
    else
        split(t -> l, l, t -> l, key), r = t;
    recalc(t);
}

void add(tnode &t, int s, int x) {
    tnode t1, t2, t3;
    split(t, t1, t3, s);
    t2 = new node(s, x);
    merge(t1, t1, t2);
    merge(t, t1, t3);
}

void del(tnode &t, int key) { // del <= key
    cout << "IN" << endl;
    cout << key << ' ' << t << ' ' << mx(t) << ' ' << (t ? t -> key : -1) << endl;
    if (!t)
        return;
    if (t -> key > key)
        del(t -> l, key);
    else {
        cout << "M!" << endl;
        del(t -> r, key);
        cout << "MIDDLE" << endl;
        t = t -> r;
    }
    recalc(t);
    cout << key << ' ' << t << ' ' << mx(t) << endl;
    cout << "OUT" << endl;
}

pair<int, int> get(tnode t) {
    if (!t)
        return {-1, -1};
    if (t -> val == t -> mx)
        return {t -> key, t -> val};
    if (t -> mx == mx(t -> l))
        return get(t -> l);
    return get(t -> r);
}

signed main() {
    gen.seed(time(0));/*
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);*/
    cin >> n;
    for (int i = 1; i <= n; i++)
        cin >> a[i];
    sort(a + 1, a + n + 1);
    multiset<pair<int, int> > q;
    //q.insert({a[1] + a[2] + a[3] + a[4] - a[5], a[5]});
    tnode root = 0;
    add(root, a[1] + a[2] + a[3] + a[4] - a[5], a[5]);
    multiset<int> suff;
    for (int i = 7; i <= n; i++)
        suff.insert(a[i]);

    int ans = -1;
    for (int i = 6; i < 7; i++) {
        cout << "FOR" << i << endl;
        del(root, a[i]);
        //cout << 1111 << endl;
        pair<int, int> res = get(root);
        int mx = res.second, sum = res.first + 2 * res.second;

        if (mx != -1) {
            auto it = suff.lower_bound(mx + a[i]);
            if (it == suff.begin())
                continue;
            it--;
            ans = max(ans, sum + a[i] + *it);
        }
        add(root, a[i - 4] + a[i - 3] + a[i - 2] + a[i - 1] - a[i], a[i]);
        suff.erase(suff.find(a[i + 1]));
    }
    cout << ans;
    return 0;
}