#include <algorithm>
#include <complex>
#include <cstdlib>
#include <ctime>
#include <time.h>
#include <iomanip>
#include <iostream>
#include <map>
#include <math.h>
#include <queue>
#include <random>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <vector>

using namespace std;
#define SAY_YES cout << "YES" << endl;
#define SAY_Yes cout << "Yes" << endl;
#define SAY_NO cout << "NO" << endl;
#define SAY_No cout << "No" << endl;
#define IFYES(TRUE_OR_FALSE)   \
    if (TRUE_OR_FALSE)         \
    {                          \
        cout << "YES" << endl; \
    }                          \
    else                       \
    {                          \
        cout << "NO" << endl;  \
    }
#define IFYes(TRUE_OR_FALSE)   \
    if (TRUE_OR_FALSE)         \
    {                          \
        cout << "Yes" << endl; \
    }                          \
    else                       \
    {                          \
        cout << "No" << endl;  \
    }
#define IFyes(TRUE_OR_FALSE)   \
    if (TRUE_OR_FALSE)         \
    {                          \
        cout << "yes" << endl; \
    }                          \
    else                       \
    {                          \
        cout << "no" << endl;  \
    }
#define DEBUG_OUTPUT_ARRAY(XXX, ONE)                            \
    for (int i = 0; i < (ONE); i++)                             \
    {                                                           \
        cout << "DEBUG: i = " << i << " -> " << XXX[i] << endl; \
    }
#define DEBUG_OUTPUT_ARRAY2(XXX, ONE, TWO)                             \
    for (int i = 0; i < (ONE); i++)                                    \
    {                                                                  \
        cout << "<<< i = " << i << " >>>" << endl;                     \
        for (int j = 0; j < (TWO); j++)                                \
        {                                                              \
            cout << "DEBUG: j = " << j << " -> " << XXX[i][j] << endl; \
        }                                                              \
    }
#define DEBUG_OUTPUT_ARRAY2_BOX(XXX, ONE, TWO) \
    for (int i = 0; i < (ONE); i++)            \
    {                                          \
        cout << i << "  ";                     \
        for (int j = 0; j < (TWO); j++)        \
        {                                      \
            cout << XXX[i][j] << " ";          \
        }                                      \
        cout << endl;                          \
    }

typedef pair<long long int, long long int> pll;


const long long int mod = 1000000007;
const long long int INF = 99999999999999999;



long long int N,M;

long long int H,W,A[210005]={},Q,sum[210005]={},res=INF;




int main()
{
    cout << fixed << setprecision(18);
   cin>>N;
   for(long long int i = 1; i <= N; i++){
       cin>>A[i];
   }
   for(long long int i = 1; i <= N; i++){
       sum[i]=sum[i-1]+A[i];
   }
   for(long long int i = 2; i <= N-2; i++){
       long long int p=1,q=i,pq;
       while(q-p>1){
           pq=(p+q)/2;
           if(sum[pq]*2>=sum[i]){
               q=pq;
           }else{
               p=pq;
           }
       }
       long long int P=sum[p],Q=sum[i]-sum[p];
        if(q!=i&&abs(sum[i]-2*sum[p+1])<=Q-P){
            P=sum[p+1];
            Q=sum[i]-sum[p+1];
        }
       long long int r=i+1,s=N,rs;
       while(s-r>1){
           rs=(r+s)/2;
           if((sum[rs]-sum[i])*2>=sum[N]-sum[i]){
               s=rs;
           }else{
               r=rs;
           }
       }
        long long int R=sum[r]-sum[i],S=sum[N]-sum[r];
        //cout<<R<<" "<<S<<endl;
        if(s!=N&&abs(sum[N]-2*sum[r+1]+sum[i])<=S-R){
            R=sum[r+1]-sum[i];
            S=sum[N]-sum[r+1];
        }
        //cout<<i<<" "<<P<<" "<<Q<<" "<<R<<" "<<S<<endl;
        res=min(res,max({P,Q,R,S})-min({P,Q,R,S}));
   }
   cout<<res<<endl;
}

#include<iostream>
#include<string.h>
#include<string>
#include<stdio.h>
#include<algorithm>
#include<vector>
#include<bitset>
#include<math.h>
#include<stack>
#include<queue>
#include<set>
#include<map>
using namespace std;
typedef long long ll;
typedef long double db;
typedef vector<int> vi;
typedef pair<int,int> pii;
const int N=200000+100;
const db pi=acos(-1.0);
#define lowbit(x) (x)&(-x)
#define sqr(x) (x)*(x)
#define rep(i,a,b) for (register int i=a;i<=b;i++)
#define per(i,a,b) for (register int i=a;i>=b;i--)
#define go(u,i) for (register int i=head[u],v=sq[i].to;i;i=sq[i].nxt,v=sq[i].to)
#define fir first
#define sec second
#define mkp make_pair
#define pb push_back
#define maxd 998244353
#define eps 1e-8
inline int read()
{
    int x=0,f=1;char ch=getchar();
    while ((ch<'0') || (ch>'9')) {if (ch=='-') f=-1;ch=getchar();}
    while ((ch>='0') && (ch<='9')) {x=x*10+(ch-'0');ch=getchar();}
    return x*f;
}

namespace My_Math{
	#define N 100000

	int fac[N+100],invfac[N+100];

	int add(int x,int y) {return x+y>=maxd?x+y-maxd:x+y;}
	int dec(int x,int y) {return x<y?x-y+maxd:x-y;}
	int mul(int x,int y) {return 1ll*x*y%maxd;}
	ll qpow(ll x,int y)
	{
		ll ans=1;
		while (y)
		{
			if (y&1) ans=mul(ans,x);
			x=mul(x,x);y>>=1;
		}
		return ans;
	}
	int getinv(int x) {return qpow(x,maxd-2);}

	int C(int n,int m)
	{
		if ((n<m) || (n<0) || (m<0)) return 0;
		return mul(mul(fac[n],invfac[m]),invfac[n-m]);
	}

	void math_init()
	{
		fac[0]=invfac[0]=1;
		rep(i,1,N) fac[i]=mul(fac[i-1],i);
		invfac[N]=getinv(fac[N]);
		per(i,N-1,1) invfac[i]=mul(invfac[i+1],i+1);
	}
	#undef N
}
using namespace My_Math;

int n,a[N];
ll sum[N];

ll calc(int l,int r) {return sum[r]-sum[l-1];}

int main()
{
	n=read();
	rep(i,1,n) a[i]=read();
	rep(i,1,n) sum[i]=sum[i-1]+a[i];
	int l=1,r=3;
	ll ans=1e18;
	rep(i,2,n-2)
	{
		while ((l+2<=i) && (abs(calc(1,l)-calc(l+1,i))>abs(calc(1,l+1)-calc(l+2,i)))) l++;
		while ((r+2<=n) && (abs(calc(i+1,r)-calc(r+1,n))>abs(calc(i+1,r+1)-calc(r+2,n)))) r++;
		ll mx=0,mn=1e18,x;
		x=calc(1,l);mx=max(mx,x);mn=min(mn,x);
		x=calc(l+1,i);mx=max(mx,x);mn=min(mn,x);
		x=calc(i+1,r);mx=max(mx,x);mn=min(mn,x);
		x=calc(r+1,n);mx=max(mx,x);mn=min(mn,x);
		ans=min(ans,mx-mn);
	}
	printf("%lld\n",ans);
	return 0;
}
	

