using System;
using System.Collections;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Numerics;
using System.Runtime.CompilerServices;
using System.Text;
using System.Threading.Tasks;

namespace AtCorder
{
	public class Program
	{
		static void Main(string[] args)
		{
			var cin = new Scanner2();
			int n = cin.Int();
			long[] a = cin.ArrayLong(n);

			long sum = a.Sum();
			var ruiL = new long[n + 1];
			var ruiR = new long[n + 1];
			for (int i = 0; i < n; i++) {
				ruiL[i + 1] = a[i] + ruiL[i];
				ruiR[i + 1] = a[n - 1 - i] + ruiR[i];
			}

			long ans = sum;
			for (int i = 1; i < n - 2; i++) {
				long leftSum = ruiL[i + 1];
				long rightSum = sum - leftSum;
				int li = BinarySearchIntL(0, i, mid => ruiL[mid + 1] <= leftSum / 2);
				int ri = BinarySearchIntL(
					i + 1, n - 1, mid => ruiL[mid + 1] - ruiL[i + 1] <= rightSum / 2);

				for (int j = 0; j < 2; j++) {
					for (int k = 0; k < 2; k++) {
						long l1 = j == 0 || li == i ? ruiL[li + 1] : ruiL[li + 2];
						long l2 = leftSum - l1;
						long r1 = k == 0 || ri == n - 2 
							? ruiL[ri + 1] - ruiL[i + 1]
							: ruiL[ri + 2] - ruiL[i + 1];
						long r2 = rightSum - r1;
						
						long min = Math.Min(l1, Math.Min(l2, Math.Min(r1, r2)));
						long max = Math.Max(l1, Math.Max(l2, Math.Max(r1, r2)));
						ans = Math.Min(ans, max - min);
					}
				}
			}

			Console.WriteLine(ans);
		}

		[MethodImpl(MethodImplOptions.AggressiveInlining)]
		public static int BinarySearchIntL(int ok, int ng, Func<int, bool> check)
		{
			while (ng - ok > 1) {
				int mid = (ok + ng) / 2;
				if (check(mid)) {
					ok = mid;
				} else {
					ng = mid;
				}
			}

			return ok;
		}
	}

	public static class Helper
	{
		public static void UpdateMin32<T>(T array, int index, int value) where T : IList<int>
			=> array[index] = Math.Min(array[index], value);
		public static void UpdateMax32<T>(T array, int index, int value) where T : IList<int>
			=> array[index] = Math.Max(array[index], value);
		public static void UpdateMin64<T>(T array, int index, long value) where T : IList<long>
			=> array[index] = Math.Min(array[index], value);
		public static void UpdateMax64<T>(T array, int index, long value) where T : IList<long>
			=> array[index] = Math.Max(array[index], value);

		public static T[] Array<T>(int n, Func<int, T> init)
			=> Enumerable.Range(0, n).Select(x => init(x)).ToArray();
		public static List<T> List<T>(int n, Func<int, T> init)
			=> Enumerable.Range(0, n).Select(x => init(x)).ToList();

		private static readonly int[] delta4_ = { 1, 0, -1, 0, 1 };
		public static void DoAt4(int i, int j, int imax, int jmax, Action<int, int> action)
		{
			for (int n = 0; n < 4; n++) {
				int ii = i + delta4_[n];
				int jj = j + delta4_[n + 1];
				if ((uint)ii < (uint)imax && (uint)jj < (uint)jmax) {
					action(ii, jj);
				}
			}
		}
	}

	public class Scanner2
	{
		private readonly char[] delimiter_ = new char[] { ' ' };
		private readonly string filePath_;
		private readonly Func<string> reader_;
		private string[] buf_;
		private int index_;

		public Scanner2(string file = "")
		{
			if (string.IsNullOrWhiteSpace(file)) {
				reader_ = Console.ReadLine;
			} else {
				filePath_ = file;
				var fs = new StreamReader(file);
				reader_ = fs.ReadLine;
			}
			buf_ = new string[0];
			index_ = 0;
		}

		public string Next()
		{
			if (index_ < buf_.Length) {
				return buf_[index_++];
			}

			string st = reader_();
			while (st == "") {
				st = reader_();
			}

			buf_ = st.Split(delimiter_, StringSplitOptions.RemoveEmptyEntries);
			if (buf_.Length == 0) {
				return Next();
			}

			index_ = 0;
			return buf_[index_++];
		}

		public int Int() => int.Parse(Next());
		public long Long() => long.Parse(Next());
		public double Double() => double.Parse(Next());

		public int[] ArrayInt(int N, int add = 0)
		{
			int[] Array = new int[N];
			for (int i = 0; i < N; i++) {
				Array[i] = Int() + add;
			}
			return Array;
		}

		public long[] ArrayLong(int N, long add = 0)
		{
			long[] Array = new long[N];
			for (int i = 0; i < N; i++) {
				Array[i] = Long() + add;
			}
			return Array;
		}

		public double[] ArrayDouble(int N, double add = 0)
		{
			double[] Array = new double[N];
			for (int i = 0; i < N; i++) {
				Array[i] = Double() + add;
			}
			return Array;
		}

		public void Save(string text)
		{
			if (string.IsNullOrWhiteSpace(filePath_)) {
				return;
			}

			File.WriteAllText(filePath_ + "_output.txt", text);
		}
	}
}

Measured memory_bytes: 34908