#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int (i) = 0 ; (i) < (int)(n) ; (i)++)
#define REP(i,a,b) for(int (i) = a ; (int)(i) <= (int)(b) ; (i)++)
#define all(n) (n).begin(),(n).end()
typedef long long ll;
typedef vector<int> Vi;
typedef vector<Vi> VVi;
typedef pair<long long,long long> Pii;
typedef vector<Pii> VPii;

int main(){
	ll N;
	cin >> N;
	ll dp[1010];
	
	for(int i = 0 ; i < N ; i++){	
		ll v;
		cin >> v;
		dp[i] = v;
		for(int j = 0 ; j < i-1 ; j++){
			dp[i] = max(dp[j]+v,dp[i]);
		}
	}
	ll ans = 0;
	for(int i = 0 ; i < N ; i++)
		ans = max(ans,dp[i]);
	cout << ans << endl;
	
	
}