#include<bits/stdc++.h>
using namespace std;
int n,a[10005],dp[10005],yu;
int main(){
    cin>>n;
    for(int i=1;i<=n;i++){
        cin>>a[i];
        dp[i]=a[i];
        for(int j=1;j<=i-2;j++){
            dp[i]=max(dp[i],dp[j]+a[i]);
        }
        yu=max(yu,dp[i]);
    }
    cout<<yu;
}
/**************************************************************
	Problem: 1653
	User: huangsheng
	Language: C++
	Result: Accepted
	Time:22 ms
	Memory:2152 kb
****************************************************************/