#include <cstdio>
#define N 100005
using namespace std;

typedef long long ll;

const ll inf = 1000000000000000000;

int n;
int val[N];
ll dp[N];
ll ans = -inf;

void bemax(ll &a, ll b) {
	a = a > b ? a : b;
}

int main() {
	scanf("%d", &n);
	
	for(int i = 1; i <= n; ++i) {
		scanf("%d", &val[i]);
		dp[i] = -inf;
	}
	
	for(int i = 1; i <= n; ++i)
		for(int j = i; j > 0; --j)
			bemax(dp[j], ll(dp[j - 1] + val[i] * j));
	
	for(int i = 1; i <= n; ++i)
		bemax(ans, dp[i]);
	
	printf("%lld\n", ans);
	
	return 0;
}