/*
ID: hepic
PROG: ariprog
LANG: C++11
*/
#include<bits/stdc++.h>

#define FOR(i,a,b) for(auto i=a; i!=b+1-2*(a>b); i+=1-2*(a>b))
#define REP(i,a,b) for(auto i=a-(a>b); i!=b-(a>b); i+=1-2*(a>b))
#define ALL(v) v.begin(),v.end()
#define what_is(x) cout<<#x<<" is "<<x<<endl;
#define min3(a,b,c) min(min(a,b),c)
#define SIZE 1000010
#define MAXN 1000000010
#define PI 3.141592653589793
#define open_read1 freopen("C:\\Users\\Hepic\\Desktop\\a.txt","r",stdin)
#define open_read freopen("ariprog.in","r",stdin)
#define open_write freopen("ariprog.out","w",stdout)

using namespace std;


typedef long long LL;
typedef pair<int,int> PII;

LL N;
LL payment[SIZE];
LL dp_val[SIZE];
LL ptrA,ptrB;
LL sumA,sumB,sumC;
LL NsumA,NsumC;
LL min_of_max_sum=-1;


int main()
{
    open_read1;
    scanf("%lld",&N);

    scanf("%lld",&payment[0]);
    dp_val[0]=payment[0];
    for(int i=1; i<N; ++i)
    {
        scanf("%lld",&payment[i]);
        dp_val[i]=dp_val[i-1]+payment[i];
    }


    ptrA=N/3;
    ptrB=(2*N)/3;


    for(int times=1; times<=N; ++times)
    {
        sumA=dp_val[ptrA];
        sumB=dp_val[ptrB]-dp_val[ptrA];
        sumC=dp_val[N-1]-dp_val[ptrB];


        if(sumA>max(sumB,sumC))
        {
            if(min_of_max_sum==-1 || sumA<min_of_max_sum)
                min_of_max_sum=sumA;

            --ptrA;
        }

        else if(sumB>max(sumA,sumC))
        {
            if(min_of_max_sum==-1 || sumB<min_of_max_sum)
                min_of_max_sum=sumB;


            NsumA=dp_val[ptrA+1];
            NsumC=dp_val[N-1]-dp_val[ptrB-1];

            if(NsumC<=NsumA)
                --ptrB;
            else
                ++ptrA;

        }

        else if(sumC>max(sumA,sumB))
        {
            if(min_of_max_sum==-1 || sumC<min_of_max_sum)
                min_of_max_sum=sumC;

            ++ptrB;
        }
    }

    printf("%lld",min_of_max_sum);


    return 0;
}