#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <string>
#include <cmath>
#include <algorithm>
#include <vector>
#include <queue>
#include <stack>
#include <map>
#include <set>
#include <cstring>

typedef long long ll;
using namespace std;

#define mod 1000000009
#define INF 10000000
#define LLINF 2000000000000000000LL

#define SIZE 10001

int main(){
    int n,v[1002];
    int dp[1002]={0},ans=0;
    
    scanf("%d",&n);
    
    for(int i=2;i<=n+1;i++) scanf("%d",&v[i]);
    
    for(int i=2;i<=n+1;i++){
        for(int j=0;j<=i-2;j++)
            dp[i] = max(dp[i],dp[j]+v[i]);
        
        ans =max(dp[i],ans);
    }
    
    printf("%d\n",ans);
    
    return 0;
}