using System;
using System.Collections.Generic;
using System.Linq;
using BitArray = System.Collections.BitArray;
using BigInteger = System.Numerics.BigInteger;
using TextReader = System.IO.TextReader;

namespace AtCoderProject
{
    public class Program
    {
        public object Calc()
        {
            var N = consoleReader.Int;
            var a = consoleReader.Split.Int;
            var sums = new long[a.Length];
            sums[0] = a[0];
            for (int i = 1; i < sums.Length; i++)
                sums[i] = a[i] + sums[i - 1];

            var pq = 0;
            var rs = 2;
            var min = long.MaxValue;
            for (int i = 1; i < sums.Length - 2; i++)
            {
                while (pq < i - 1)
                {
                    var pq1 = Math.Abs(sums[pq] - (sums[i] - sums[pq]));
                    var pq2 = Math.Abs(sums[pq + 1] - (sums[i] - sums[pq + 1]));
                    if (pq2 < pq1) ++pq;
                    else break;
                }
                while (rs < sums.Length - 1)
                {
                    var rs1 = Math.Abs((sums[rs] - sums[i]) - (sums[sums.Length - 1] - sums[rs]));
                    var rs2 = Math.Abs((sums[rs + 1] - sums[i]) - (sums[sums.Length - 1] - sums[rs + 1]));
                    if (rs2 < rs1) ++rs;
                    else break;
                }
                var pqrs = new[] { sums[pq], sums[i] - sums[pq], sums[rs] - sums[i], sums[sums.Length - 1] - sums[rs] };
                Array.Sort(pqrs);
                min = Math.Min(min, pqrs.Last() - pqrs.First());
            }

            return min;
        }


        #region いつもの
        private readonly ConsoleReader consoleReader;
        public Program(ConsoleReader consoleReader) { this.consoleReader = consoleReader; }
        static void Main() => Console.WriteLine(new Program(new ConsoleReader(Console.In)).Calc()); static string AllLines<T>(IEnumerable<T> source) => string.Join("\n", source);
        #endregion
    }

#pragma warning disable
    public class ConsoleReader
    {
        private string[] line = Array.Empty<string>();
        private int linePosition;
        private TextReader textReader;
        public ConsoleReader(TextReader tr) { textReader = tr; }
        public int Int => int.Parse(String);
        public long Long => long.Parse(String);
        public double Double => double.Parse(String);
        public string String
        {
            get
            {
                if (linePosition >= line.Length)
                {
                    linePosition = 0;
                    line = textReader.ReadLine().Split();
                }
                return line[linePosition++];
            }
        }
        public class SplitLine
        {
            private string[] splited;
            public SplitLine(ConsoleReader cr) { splited = cr.textReader.ReadLine().Split(); }
            public int[] Int => String.Select(x => int.Parse(x)).ToArray();
            public long[] Long => String.Select(x => long.Parse(x)).ToArray();
            public double[] Double => String.Select(x => double.Parse(x)).ToArray();
            public string[] String => splited;
        }
        public SplitLine Split => new SplitLine(this);
        public class RepeatReader
        {
            ConsoleReader cr; int count;
            public RepeatReader(ConsoleReader cr, int count) { this.cr = cr; this.count = count; }
            public IEnumerable<T> Select<T>(Func<ConsoleReader, T> func) { for (int i = 0; i < count; i++) yield return func(cr); }
            public IEnumerable<string> String { get { for (int i = 0; i < count; i++) yield return cr.String; } }
            public IEnumerable<int> Int { get { for (int i = 0; i < count; i++) yield return cr.Int; } }
            public IEnumerable<double> Double { get { for (int i = 0; i < count; i++) yield return cr.Double; } }
        }
        public RepeatReader Repeat(int count) => new RepeatReader(this, count);
    }
}

Measured memory_bytes: 36060