#include <bits/stdc++.h>
#define ll long long
#define pb push_back

using namespace std;

int main()
{
    ios_base::sync_with_stdio(false);
	cin.tie(nullptr);
	cout.tie(nullptr);

	int n;
	cin >> n;

	vector<int> a(n);
	for(int i=0; i<n; i++) cin >> a[i];
	sort(a.begin(), a.end());

	int ans = -1, i;
	for(i=n-1; i>=6; i--)
    {
        if(a[i] < a[i-1] + a[i-2] && a[i-1] + a[i-2] < a[i-3] + a[i-4] + a[i-5] + a[i-6])
        {
            ans = a[i] + a[i-1] + a[i-2] + a[i-3] + a[i-4] + a[i-5] + a[i-6];
            break;
        }
    }

    if(i >= 6)
    {
        for(int j=n-1; j>=0; j--)
        {
            int tl = a[j] - a[i - 2], tr = a[i - 3] + a[i - 4] + a[i - 5] + a[i - 6] - a[i - 2];
            if(tr - tl < 2) continue;

            int l = i - 1, r = j - 1;
            while(l != r)
            {
                int m = (l + r + 1) / 2;

                if(a[m] >= tr) r = m - 1;
                else l = m;
            }

            if(a[l] > tl)
            {
                ans = max(ans, a[j] + a[l] + a[i - 2] + a[i - 3] + a[i - 4] + a[i - 5] + a[i - 6]);
            }
        }
    }

    cout << ans;
}