// Slower C++ solution:
#include<bits/stdc++.h>

using namespace std;

const int maxn=2e5+25;

#define ll long long int

#define INF 0x3f3f3f3f

int n;

int a[maxn];

ll sum[maxn];

ll b[5];

int main()

{

    int n;

    scanf("%d",&n);

    memset(sum,0,sizeof sum);

    for(int i=1;i<=n;i++){

        scanf("%d",&a[i]);

        sum[i]=sum[i-1]+a[i];

    }

    ll ans=-1;

    for(int i=2;i<=n-1;i++){

        ll s1=sum[i];

        ll s2=sum[n]-sum[i];

        ll x1,x2,y1,y2;

        ll av1=s1/2;ll av2=s2/2;

        // 1.0

        x1=lower_bound(sum+1,sum+i+1,av1)-sum;

        y1=lower_bound(sum+i+2,sum+1+n,s1+av2)-sum;

       // cout<<x1<<" "<<y1<<endl;

        b[1]=sum[x1];

        b[2]=s1-sum[x1];

        b[3]=sum[y1]-s1;

        b[4]=s2-b[3];

        //cout<<b[1]<<" "<<b[2]<<" "<<b[3]<<" "<<b[4]<<endl;

        sort(b+1,b+5);

        //cout<<b[1]<<" "<<b[2]<<" "<<b[3]<<" "<<b[4]<<endl;

        if(ans==-1){

            ans=abs(b[4]-b[1]);

        }

        ans=min(ans,abs(b[4]-b[1]));

        //cout<<ans<<endl;





        x1=lower_bound(sum+1,sum+i+1,av1)-sum;

        y1=lower_bound(sum+i+2,sum+1+n,s1+av2)-sum;

       // cout<<x1<<" "<<y1<<endl;

        x1--;y1--;

        b[1]=sum[x1];

        b[2]=s1-sum[x1];

        b[3]=sum[y1]-s1;

        b[4]=s2-b[3];

        //cout<<b[1]<<" "<<b[2]<<" "<<b[3]<<" "<<b[4]<<endl;

        sort(b+1,b+5);

        //cout<<b[1]<<" "<<b[2]<<" "<<b[3]<<" "<<b[4]<<endl;

        if(ans==-1){

            ans=abs(b[4]-b[1]);

        }

        ans=min(ans,abs(b[4]-b[1]));







        x1=lower_bound(sum+1,sum+i+1,av1)-sum;

        y1=lower_bound(sum+i+2,sum+1+n,s1+av2)-sum;

       // cout<<x1<<" "<<y1<<endl;

        x1--;

        b[1]=sum[x1];

        b[2]=s1-sum[x1];

        b[3]=sum[y1]-s1;

        b[4]=s2-b[3];

        //cout<<b[1]<<" "<<b[2]<<" "<<b[3]<<" "<<b[4]<<endl;

        sort(b+1,b+5);

        //cout<<b[1]<<" "<<b[2]<<" "<<b[3]<<" "<<b[4]<<endl;

        if(ans==-1){

            ans=abs(b[4]-b[1]);

        }

        ans=min(ans,abs(b[4]-b[1]));





        x1=lower_bound(sum+1,sum+i+1,av1)-sum;

        y1=lower_bound(sum+i+2,sum+1+n,s1+av2)-sum;

       // cout<<x1<<" "<<y1<<endl;

        y1--;

        b[1]=sum[x1];

        b[2]=s1-sum[x1];

        b[3]=sum[y1]-s1;

        b[4]=s2-b[3];

        //cout<<b[1]<<" "<<b[2]<<" "<<b[3]<<" "<<b[4]<<endl;

        sort(b+1,b+5);

        //cout<<b[1]<<" "<<b[2]<<" "<<b[3]<<" "<<b[4]<<endl;

        if(ans==-1){

            ans=abs(b[4]-b[1]);

        }

        ans=min(ans,abs(b[4]-b[1]));



        //2.0

        av1=s1/2;av2=s2/2;

        x1=upper_bound(sum+1,sum+i+1,av1)-sum;

        y1=lower_bound(sum+i+2,sum+1+n,s1+av2)-sum;

       // cout<<x1<<" "<<y1<<endl;

        b[1]=sum[x1];

        b[2]=s1-sum[x1];

        b[3]=sum[y1]-s1;

        b[4]=s2-b[3];

        //cout<<b[1]<<" "<<b[2]<<" "<<b[3]<<" "<<b[4]<<endl;

        sort(b+1,b+5);

        //cout<<b[1]<<" "<<b[2]<<" "<<b[3]<<" "<<b[4]<<endl;

        if(ans==-1){

            ans=abs(b[4]-b[1]);

        }

        ans=min(ans,abs(b[4]-b[1]));



        //3.0

        av1=s1/2;av2=s2/2;

        x1=lower_bound(sum+1,sum+i+1,av1)-sum;

        y1=upper_bound(sum+i+2,sum+1+n,s1+av2)-sum;

       // cout<<x1<<" "<<y1<<endl;

        b[1]=sum[x1];

        b[2]=s1-sum[x1];

        b[3]=sum[y1]-s1;

        b[4]=s2-b[3];

        //cout<<b[1]<<" "<<b[2]<<" "<<b[3]<<" "<<b[4]<<endl;

        sort(b+1,b+5);

        //cout<<b[1]<<" "<<b[2]<<" "<<b[3]<<" "<<b[4]<<endl;

        if(ans==-1){

            ans=abs(b[4]-b[1]);

        }

        ans=min(ans,abs(b[4]-b[1]));



        //4.0

        av1=s1/2;av2=s2/2;

        x1=upper_bound(sum+1,sum+i+1,av1)-sum;

        y1=upper_bound(sum+i+2,sum+1+n,s1+av2)-sum;

       // cout<<x1<<" "<<y1<<endl;

        b[1]=sum[x1];

        b[2]=s1-sum[x1];

        b[3]=sum[y1]-s1;

        b[4]=s2-b[3];

        //cout<<b[1]<<" "<<b[2]<<" "<<b[3]<<" "<<b[4]<<endl;

        sort(b+1,b+5);

        //cout<<b[1]<<" "<<b[2]<<" "<<b[3]<<" "<<b[4]<<endl;

        if(ans==-1){

            ans=abs(b[4]-b[1]);

        }

        ans=min(ans,abs(b[4]-b[1]));



    }

    printf("%lld\n",ans);

    return 0;

}


// Faster C++ solution for the same problem (measured speedup: 2.6302006109037563x):
#define _CRT_SECURE_NO_WARNINGS

#include <iostream>

#include <algorithm>

#include <string>

#include <vector>

#include <stack>

#include <deque>

#include <queue>

#include <list>

#include <limits>

#include <set>

#include <map>

#include <functional>



#include <inttypes.h>

#include <limits.h>

#include <stdint.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <math.h>



using namespace std;

typedef long long ll;



#ifndef PRId64

#define PRId64 "lld"

#endif

#ifndef SCNd64

#define SCNd64 "lld"

#endif

#define SC sc()

#define PT pr()

#define FORi(i,b,e) for (int i = (b), _ = (e); i < _; ++i)

#define FORe(i,b,e) for (int i = (b), _ = (e); i <= _; ++i)

#define FORre(i,b,e) for (int i = (b), _ = (e); i >= _; --i)



static int sc_ret = 0;

struct sc

{

    sc& operator()(char& v) { v = sc_ret = getchar(); return *this; }

    sc& operator()(int& v) { sc_ret = scanf("%d", &v); return *this; }

    sc& operator()(unsigned& v) { sc_ret = scanf("%u", &v); return *this; }

    sc& operator()(double& v) { sc_ret = scanf("%lf", &v); return *this; }

    sc& operator()(char* v) { sc_ret = scanf("%s", v); return *this; }

    sc& operator()(string& v) { sc_ret = (bool)(cin >> v); return *this; }

    sc& operator()(ll& v) { sc_ret = scanf("%" SCNd64, &v); return *this; }

    sc& ch(char& v) { sc_ret = scanf(" %c", &v); return *this; }

    sc& gets(char* v) { sc_ret = fgets(v, INT_MAX, stdin) != 0; v[strlen(v) - 1] = 0; return *this; }

    operator bool() const { return sc_ret > 0; }

    void read(int& v)

    {

        int x = 0, k = 1;

        char c = getchar();

        while (c < '0' || c > '9')

        {

            if (c == '-') k = -1;

            c = getchar();

        }

        while (c >= '0' && c <= '9') x = (x << 3) + (x << 1) + (c - 48), c = getchar();

        v = x * k;

    }

};

struct pr

{

    pr& ln() { putchar('\n'); return *this; }

    pr& operator()(char v) { putchar(v); return *this; }

    pr& operator()(int v) { printf("%d", v); return *this; }

    pr& operator()(double v) { printf("%.2f", v); return *this; }

    pr& operator()(const char* fmt, double v) { printf(fmt, v); return *this; }

    pr& operator()(const char* v) { printf("%s", v);return *this; }

    pr& operator()(string v) { printf("%s", v.c_str());return *this; }

    pr& operator()(ll v) { printf("%" PRId64, v);return *this; }



    void write(int v)

    {

        int cnt = 0; char c[15];

        if (v == 0)

        {

            putchar('0');

            return;

        }

        if (v < 0) putchar('-'), v = -v;

        while (v) c[++cnt] = (v % 10) + 48, v /= 10;

        while (cnt > 0) putchar(c[cnt--]);

    }

    template <typename T>

    void ln(T* arr, int size)

    {

        if (size > 0)

        {

            (*this)(arr[0]);

            for (int i = 1; i < size; ++i)

            {

                putchar(' ');

                (*this)(arr[i]);

            }

            putchar('\n');

        }

    }



    template <typename T>

    void muln(T* arr, int size)

    {

        for (int i = 0; i < size; ++i)

        {

            (*this)(arr[i]);

            putchar('\n');

        }

    }

};



const int inf = 0x3f3f3f3f;

const int mod = 1000000007;

const int maxn = 200000 + 10;

const int maxm = 100000 + 10;



ll a[maxn];



void getlr(int n, int m, int& l, int& r)

{

    l = (int)(lower_bound(a + 1, a + m - 1, a[m] / 2) - a);

    if (l > 1 && min(a[l], a[m] - a[l]) < min(a[l - 1], a[m] - a[l - 1])) --l;

    r = (int)(lower_bound(a + m + 1, a + n, (a[n] - a[m]) / 2 + a[m]) - a);

    if (r > m + 1 && min(a[r] - a[m], a[n] - a[r]) < min(a[r - 1] - a[m], a[n] - a[r - 1])) --r;

}



/*

10

1 1 1 1 1 1 1 1 2 9

*/

int main()

{

    int n, t, k;

    SC(n);

    FORe(i, 1, n)

    {

        int v;

        SC.read(v);

        a[i] = v + a[i - 1];

    }

    //*

    int sl = 2, sr = n - 2;

    for (int m = (sl + sr) / 2; sl < sr - 1; m = (sl + sr) / 2)

    {

        int l, r;

        getlr(n, m, l, r);

        ll minl = min(a[l], a[m] - a[l]);

        ll minr = min(a[r] - a[m], a[n] - a[r]);

        ll maxl = max(a[l], a[m] - a[l]);

        ll maxr = max(a[r] - a[m], a[n] - a[r]);

        if (minl == minr && maxl == maxr)

        {

            sl = sr = m;

            break;

        }

        if (minl <= minr && maxl <= maxr)

        {

            sl = m;

        }

        else if (minl >= minr && maxl >= maxr)

        {

            sr = m;

        }

        else

        {

            break;

        }

    }

    //{

    //    int l1, r1;

    //    getlr(n, sl, l1, r1);

    //    ll min1 = min(min(a[l1], a[sl] - a[l1]), min(a[r1] - a[sl], a[n] - a[r1]));

    //    ll max1 = max(max(a[l1], a[sl] - a[l1]), max(a[r1] - a[sl], a[n] - a[r1]));

    //    int l2, r2;

    //    getlr(n, sr, l2, r2);

    //    ll min2 = min(min(a[l2], a[sr] - a[l2]), min(a[r2] - a[sr], a[n] - a[r2]));

    //    ll max2 = max(max(a[l2], a[sr] - a[l2]), max(a[r2] - a[sr], a[n] - a[r2]));

    //    PT(min(max1 - min1, max2 - min2));

    //}



    int l = 1, r = 3; ll ret = a[n];

    int ml = sl, mr = sr + 1;

    int c = max(2, (int)(lower_bound(a + 1, a + n, a[n] / 2) - a));

    //ml = min(n - 2, c - 1000);

    //mr = min(n - 1, c + 1000);

    l = max(1, (int)(lower_bound(a + 1, a + ml - 1, a[ml] / 2) - a) - 1);

    r = max(ml + 1, (int)(lower_bound(a + ml + 1, a + n, (a[n] - a[ml]) / 2 + a[ml]) - a) - 1);

    //l = 1; r = ml + 1;

    FORi(i, ml, mr)

    {

        for (; l < i - 1; ++l)

        {

            if (min(a[l], a[i] - a[l]) >= min(a[l + 1], a[i] - a[l + 1]))

                break;

        }

        for (; r < n - 1; ++r)

        {

            if (min(a[r] - a[i], a[n] - a[r]) >= min(a[r + 1] - a[i], a[n] - a[r + 1]))

                break;

        }

        //getlr(n, i, l, r);

        ret = min(ret, max(max(a[r] - a[i], a[n] - a[r]), max(a[l], a[i] - a[l]))

            - min(min(a[l], a[i] - a[l]), min(a[r] - a[i], a[n] - a[r])));

    }

    PT(ret);

    return 0;

}