#include <iostream>
#include <fstream>
#include <bitset>
#include <cmath>
using namespace std;

ifstream fin("recyclebin.in");
ofstream fout("recyclebin.out");

int n;
int a[1001];

void reading() {
    fin >> n;
    for(int i = 1; i <= n; i++){
        fin >> a[i];
    }
}
int big(int x){
    int p = 1, k = 0;
    while(p - 1 < x){
        p <<= 1;
        k++;
    }
    return k;
}
int dp[1001][1001];

int main() {
    reading();
    int put = big(n);
    int limit = (1 << put) - 1;
    for(int i = 1; i <= n; i++){
        for(int masc = 0; masc <= limit && masc <= i; masc++) {
            dp[i][masc] = dp[i - 1][masc] + a[i];
            bitset<10> biti(masc);
            for(int bit = 0; bit <= 9; bit++)
                if(biti[bit] == 1)
                    dp[i][masc] = max(dp[i][masc], dp[i - (1 << bit)][masc - (1 << bit)]);
        }
    }
    int ma = 0;
    for(int i = 0; i <= limit;i++) {
        ma = max(ma, dp[n][i]);
    }
    fout << ma;
}