using System;
using System.Collections.Generic;
using System.Linq;
using System.IO;
//using System.Text;
//using System.Text.RegularExpressions;
//using System.Globalization;
//using System.Diagnostics;
using static System.Console;
//using System.Numerics;
using static System.Math;
//using pair = Pair<int, int>;

class Program
{
    static void Main()
    {
        //SetOut(new StreamWriter(OpenStandardOutput()) { AutoFlush = false });
        new Program().solve();
        Out.Flush();
    }
    Scanner cin = new Scanner();
    readonly int[] dd = { 0, 1, 0, -1, 0 }; //→↓←↑
    readonly int mod = 1000000007;
    void chmax<T>(ref T a, T b) where T : IComparable<T> { a = a.CompareTo(b) < 0 ? b : a; }
    void chmin<T>(ref T a, T b) where T : IComparable<T> { a = a.CompareTo(b) < 0 ? a : b; }

    void solve()
    {
        int N = cin.nextint;
        var A = cin.scanlong;
        var B = new long[N];
        B[0] = A[0];
        for (int i = 1; i < N; i++)
        {
            B[i] = A[i] + B[i - 1];
        }

        long ans = long.MaxValue;
        for (int i = 1; i <= N - 3; i++)//iの後ろを真ん中カットとする
        {
            int x = upper_bound(B, B[i] / 2);
            var D = new long[4];
            D[0] = B[x];
            D[1] = B[i] - B[x];
            if (x > 0 && Abs(B[x - 1] - B[i] / 2) < Abs(B[x] - B[i] / 2))
            {
                D[0] = B[x - 1];
                D[1] = B[i] - B[x - 1];
            }


            var S = B[i] + (B[N - 1] - B[i]) / 2;
           
            x = upper_bound(B, S);
            D[2] = B[x] - B[i];
            D[3] = B[N - 1] - B[x];
            if (x > i + 1 && Abs(B[x - 1] - S) < Abs(B[x] - S))
            {
                D[2] = B[x - 1] - B[i];
                D[3] = B[N - 1] - B[x - 1];
            }

            if (i == 3)
            {
                //WriteLine(string.Join(" ", D));
            }
            chmin(ref ans, D.Max() - D.Min());
        }

        WriteLine(ans);
    }

    int upper_bound(long[] arr, long val)
    {
        int low = 0, high = arr.Count();
        int mid;

        while (low < high)
        {
            mid = ((high - low) >> 1) + low;
            if (arr[mid] < val) low = mid + 1;
            else high = mid;
        }
        return low;
    }

}

class Scanner
{
    string[] s; int i;
    char[] cs = new char[] { ' ' };
    public Scanner() { s = new string[0]; i = 0; }
    public string[] scan { get { return ReadLine().Split(); } }
    public int[] scanint { get { return Array.ConvertAll(scan, int.Parse); } }
    public long[] scanlong { get { return Array.ConvertAll(scan, long.Parse); } }
    public double[] scandouble { get { return Array.ConvertAll(scan, double.Parse); } }
    public string next
    {
        get
        {
            if (i < s.Length) return s[i++];
            string st = ReadLine();
            while (st == "") st = ReadLine();
            s = st.Split(cs, StringSplitOptions.RemoveEmptyEntries);
            i = 0;
            return next;
        }
    }
    public int nextint { get { return int.Parse(next); } }
    public long nextlong { get { return long.Parse(next); } }
    public double nextdouble { get { return double.Parse(next); } }
}

Measured memory_bytes: 35548