#include <iostream>

#include <cstring>

#include <cstdio>

#include <algorithm>

using namespace std;

typedef long long ll;

ll a[] , ans , sum[];

struct TnT {

    ll one , another;

}Max[];

bool cmp(TnT x , TnT y) {

    if(x.another == y.another) return x.one < y.one;

    return x.another > y.another;

}

int main() {

    int n;

    while(~scanf("%d" , &n)) {

        sum[] = ;

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

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

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

        }

        ans = ;

        ll num[];

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

            int l1 =  , r1 = i;

            if(i == ) {

                int cnt = ;

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

                    num[] = a[l1] , num[] = sum[j] - sum[l1] , num[] = sum[n] - sum[j];

                    sort(num , num + );

                    Max[cnt].one = num[] , Max[cnt++].another = num[];

                }

                if(cnt) {

                    sort(Max , Max + cnt , cmp);

                    ans = max(ans , Max[].one);

                }

            }

            else if(i >  && i < n - ) {

                int cnt = ;

                for(int j =  ; j < i ; j++) {

                    num[] = sum[j] , num[] = sum[r1] - sum[j] , num[] = sum[n] - sum[r1];

                    sort(num , num + );

                    Max[cnt].one = num[] , Max[cnt++].another = num[];

                }

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

                    num[] = sum[r1] , num[] = sum[j] - sum[r1] , num[] = sum[n] - sum[j];

                    sort(num , num + );

                    Max[cnt].one = num[] , Max[cnt++].another = num[];

                }

                if(cnt) {

                    sort(Max , Max + cnt , cmp);

                    ans = max(ans , Max[].one);

                }

            }

            else {

                int cnt = ;

                for(int j =  ; j < i ; j++) {

                    num[] = a[n] , num[] = sum[j] , num[] = sum[r1] - sum[j];

                    sort(num , num + );

                    Max[cnt].one = num[] , Max[cnt++].another = num[];

                }

                if(cnt) {

                    sort(Max , Max + cnt , cmp);

                    ans = max(ans , Max[].one);

                }

            }

        }

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

        //printf("%I64d\n" , ans);

    }

    return ;

}