using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static long NN => long.Parse(ReadLine());
    static long[] NList => ReadLine().Split().Select(long.Parse).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var n = NN;
        var s = ReadLine().Split();
        var a = new long[n];
        if (s.Length == n)
        {
            WriteLine("\"assert\"");
            return;
        }
        else
        {
            a[0] = long.Parse(s[0]);
            for (var i = 1; i < n; ++i) a[i] = NN;
        }
        var set = new HashSet<long>();
        for (var i = 0; i < n; ++i) for (var j = i + 1; j < n; ++j) set.Add(a[i] + a[j]);
        var list = new List<long>(set);
        list.Sort();
        WriteLine(list[^2]);
    }
}