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

using namespace std;
 
template<typename T1, typename T2> istream& operator>>(istream& is, pair<T1,T2>& a){ return is >> a.first >> a.second; }
template<typename T1, typename T2> ostream& operator<<(ostream& os, pair<T1,T2>& a){ return os << a.first << " " << a.second; }
template<typename T> istream& operator>>(istream& is, vector< T >& vc){ for(int i = 0; i < vc.size(); i++) is >> vc[i]; return is; }
template<typename T> ostream& operator<<(ostream& os, vector< T >& vc){ for(int i = 0; i < vc.size(); i++) os << vc[i] << endl; return os; }
 
#define ForEach(it,c) for(__typeof (c).begin() it = (c).begin(); it != (c).end(); it++)
#define ALL(v) (v).begin(), (v).end()
#define UNQ(s) { sort(ALL(s)); (s).erase( unique( ALL(s)), (s).end());}

typedef pair< double , double > Pi;
typedef pair< double , Pi > Pii;

int main(){
  int N;
  cin >> N;
  vector< int > V(N);
  cin >> V;

  vector< int > dp(N);
  for(int i = 0; i < N; i++){
    dp[i] = V[i];
  }

  for(int i = 0; i < N; i++){
    for(int j = N - 1; j > i + 1; j--){
      dp[j] = max( dp[j], dp[i] + V[j]);
    }
  }
  cout << *max_element(ALL(dp)) << endl;
}