#include <bits/stdc++.h>

using namespace std;

int N;
int taste[1000] = {0};
int dp[1001] = {0};
int result = 0;

void rec(int number = 0, int sum = 0){
    
    if(number == (N - 1) || number == (N - 2)){
        if(result < sum) result = sum;
        if(sum == 0) result = taste[number];
        return;
    }
    
    if(dp[number] != 0 && dp[number] >= sum) return;
    dp[number] = sum;
    
    int i;
    if(number == 0 && sum == 0){
        for(i = 0; i < N; ++i){
            rec(i, sum + taste[i]);
        }
    }
    else{
        for(i = number + 1; i < N; ++i){
            if(i != (number + 1)) rec(i, sum + taste[i]);
        }
    }
    
    return;
}

int main(void){
    
    cin >> N;
    
    int i;
    for(i = 0; i < N; ++i){
        cin >> taste[i];
    }
    
    rec();
    
    cout << result << endl;
    
    return 0;
}