// https://atcoder.jp/contests/arc100/tasks/arc100_b

package main

import (
	"bufio"
	"bytes"
	"fmt"
	"os"
	"sort"
	"strconv"
	"strings"
)

func assert(a, b interface{}) {
	if a != b {
		panic("mm")
	}
}

// d: debug IO. it can print debug in test.
func solve(io *Io, d *Io) {
	N := io.NextInt()
	as := io.NextInts(N)

	// 3 つ入れる切断のうち、真ん中を固定することを考える。
	// 左右をさらに 1 度ずつ切断するが、この左右の切断後の 2 つの配列の和が最大値・最小値の候補であるから、
	// 最大値になり得るものはより小さく、最小値になり得るものはより大きくなるべきで、つまり 2 配列の和の差が最小であるのが最善。
	// 累積和を求めておけば、二分探索で境界が特定できるから O(N log N) で全通り試せる。 尺取法なら O(N) となる。

	// B: [0, cL), C: [cL, dL), D: [dL, eL): E: [eL, len)

	// sums[i]: [0, i)
	sums := make([]int, N+1)
	for i, a := range as {
		sums[i+1] = sums[i] + a
	}

	res := int(1e18)

	for dL := 2; dL+1 < N; dL++ {
		lSum := sums[dL]
		rSum := sums[N] - lSum

		// bR: lSum / 2 以上となる最小の as における index
		bR := sort.SearchInts(sums, (lSum+1)/2) - 1

		tmpB := sums[bR+1]
		tmpC := lSum - tmpB

		// B でなく C が lSum / 2 以上となった方が差が小さいケース
		if bR >= 1 && tmpB-tmpC > tmpC-tmpB+2*as[bR] {
			bR--
		}

		B := sums[bR+1]
		C := lSum - B

		dR := sort.SearchInts(sums, lSum+(rSum+1)/2) - 1

		tmpD := sums[dR+1] - lSum
		tmpE := rSum - tmpD

		if dR >= dL+1 && tmpD-tmpE > tmpE-tmpD+2*as[dR] {
			dR--
		}

		D := sums[dR+1] - lSum
		E := rSum - D

		res = Min(
			res,
			Max(B, C, D, E)-Min(B, C, D, E),
		)
	}

	io.Println(res)
}

// 尺取法
func solve2(io *Io, d *Io) {
	N := io.NextInt()
	as := io.NextInts(N)

	// B: [0, cL), C: [cL, dL), D: [dL, eL): E: [eL, len)

	// sums[i]: [0, i)
	sums := make([]int, N+1)
	for i, a := range as {
		sums[i+1] = sums[i] + a
	}

	res := int(1e18)

	cL := 0
	B := 0
	eL := 2
	D := 0

	for dL := 2; dL+1 < N; dL++ {
		lSum := sums[dL]
		rSum := sums[N] - lSum

		for cL < dL-1 {
			C := lSum - B
			nB := B + as[cL]
			nC := C - as[cL]
			if Abs(B-C) > Abs(nB-nC) {
				B += as[cL]
				cL++
			} else {
				break
			}
		}

		for eL < N-1 {
			E := rSum - D
			nD := D + as[eL]
			nE := E - as[eL]
			if Abs(D-E) > Abs(nD-nE) {
				D += as[eL]
				eL++
			} else {
				break
			}
		}

		C := lSum - B
		E := rSum - D

		res = Min(
			res,
			Max(B, C, D, E)-Min(B, C, D, E),
		)

		D -= as[dL]
	}

	io.Println(res)
}

func main() {
	io := NewIo()
	defer io.Flush()
	solve2(io, nil)
}

/* IO Helpers */

// Io combines reader, writer, & tokens as the state when processing the input
type Io struct {
	reader    *bufio.Reader
	writer    *bufio.Writer
	tokens    []string
	nextToken int
}

// NewIo creates Io with Stdin & Stdout
func NewIo() *Io {
	return &Io{
		reader: bufio.NewReader(os.Stdin),
		writer: bufio.NewWriter(os.Stdout),
	}
}

// Flush calls the writer's Flush
func (io *Io) Flush() {
	io.writer.Flush()
}

// NextLine returns the string from reader.ReadLine()
func (io *Io) NextLine() string {
	if io.nextToken < len(io.tokens) {
		panic("io.nextToken < len(io.tokens)")
	}

	var buffer bytes.Buffer

	for {
		line, isPrefix, err := io.reader.ReadLine()
		if err != nil {
			panic(err)
		}
		buffer.Write(line)
		if !isPrefix {
			break
		}
	}

	return buffer.String()
}

// NextLines returns []string from next n lines
func (io *Io) NextLines(n int) []string {
	res := make([]string, n)
	for i := 0; i < n; i++ {
		res[i] = io.NextLine()
	}
	return res
}

// Next returns the string token (partial string of the line divided by spaces)
func (io *Io) Next() string {
	if io.nextToken >= len(io.tokens) {
		line := io.NextLine()
		io.tokens = strings.Fields(line)
		io.nextToken = 0
	}

	res := io.tokens[io.nextToken]
	io.nextToken++
	return res
}

// NextStrings returns the []string from the next n tokens
func (io *Io) NextStrings(n int) []string {
	res := make([]string, n)
	for i := 0; i < n; i++ {
		res[i] = io.Next()
	}
	return res
}

// NextRunes returns next string as []rune
func (io *Io) NextRunes() []rune {
	return []rune(io.Next())
}

// NextInt returns the int from the next token
func (io *Io) NextInt() int {
	res, err := strconv.Atoi(io.Next())
	if err != nil {
		panic(err)
	}
	return res
}

// NextInts returns the []int from the next n tokens
func (io *Io) NextInts(n int) []int {
	res := make([]int, n)
	for i := 0; i < n; i++ {
		res[i] = io.NextInt()
	}
	return res
}

// NextFloat returns the float64 from the next token
func (io *Io) NextFloat() float64 {
	res, err := strconv.ParseFloat(io.Next(), 64)
	if err != nil {
		panic(err)
	}
	return res
}

// NextFloats returns the []float64 from the next n tokens
func (io *Io) NextFloats(n int) []float64 {
	res := make([]float64, n)
	for i := 0; i < n; i++ {
		res[i] = io.NextFloat()
	}
	return res
}

// Println prints the input to the writer in an easy-to-see form
func (io *Io) Println(a ...interface{}) {
	var values []string
	for i := 0; i < len(a); i++ {
		values = append(values, "%v")
	}
	io.Printfln(strings.Join(values, " "), a...)
}

// Print calls Fprint to the writer
func (io *Io) Print(a interface{}) {
	fmt.Fprint(io.writer, a)
}

// Printf calls Fprintf to the writer
func (io *Io) Printf(format string, a ...interface{}) {
	fmt.Fprintf(io.writer, format, a...)
}

// Printfln calls Fprint to the writer
func (io *Io) Printfln(format string, a ...interface{}) {
	fmt.Fprintf(io.writer, format+"\n", a...)
}

// PrintInts prints ints with space and new line at the end
func (io *Io) PrintInts(ints []int) {
	for i, e := range ints {
		io.Print(e)

		if i == len(ints)-1 {
			io.Println()
		} else {
			io.Print(" ")
		}
	}
}

// Debug calls Println and Flush immediately
func (io *Io) Debug(a ...interface{}) {
	if io == nil {
		return
	}

	io.Println(a...)
	io.Flush()
}

/* Math Helpers */

// MOD is 10^9 + 7
const MOD = 1000000007

// Max of the ints
func Max(numbers ...int) int {
	max := numbers[0]
	for i, number := range numbers {
		if i == 0 {
			continue
		}
		if number > max {
			max = number
		}
	}
	return max
}

// Min of the ints
func Min(numbers ...int) int {
	min := numbers[0]
	for i, number := range numbers {
		if i == 0 {
			continue
		}
		if min > number {
			min = number
		}
	}
	return min
}

// Sum of the ints
func Sum(numbers ...int) int {
	sum := 0

	for _, number := range numbers {
		sum += number
	}

	return sum
}

// Pow calculates the pow for int with O(log e)
func Pow(a, e int) int {
	if a < 0 || e < 0 {
		panic(fmt.Sprintf("Pow was called for a < 0 or e < 0, a: %d, e: %d", a, e))
	}

	if e == 0 {
		return 1
	}

	if e%2 == 0 {
		half := Pow(a, e/2)
		return half * half
	}

	return a * Pow(a, e-1)
}

// Abs returns the absolute value of the input
func Abs(a int) int {
	if a < 0 {
		return -a
	}

	return a
}

/* Structure Helpers */

// Set is orderless List
type Set map[interface{}]struct{}

// NewSet returns empty Set
func NewSet() *Set {
	return &Set{}
}

// Add the value to the set
func (set *Set) Add(value interface{}) {
	(*set)[value] = struct{}{}
}

// Includes check the set has the value
func (set *Set) Includes(value interface{}) bool {
	_, included := (*set)[value]
	return included
}

// Remove deletes the value from the set if exists
func (set *Set) Remove(value interface{}) {
	if !set.Includes(value) {
		return
	}

	delete(*set, value)
}

// ImmutableSort returns sorted slice without mutating original one
func ImmutableSort(slice []int) []int {
	res := make([]int, len(slice))
	copy(res, slice)
	sort.Ints(res)
	return res
}

/* Util helpers */

// Ternary is like `cond ? a : b`. should assert the returned value like `Ternary(cond, a, b).(int)`
func Ternary(cond bool, a, b interface{}) interface{} {
	if cond {
		return a
	}

	return b
}

// TernaryInt uses Ternary and assert the value as int
func TernaryInt(cond bool, a, b int) int {
	return Ternary(cond, a, b).(int)
}

// TernaryString uses Ternary and assert the value as string
func TernaryString(cond bool, a, b string) string {
	return Ternary(cond, a, b).(string)
}


Measured memory_bytes: 9344