#include<bits/stdc++.h>

using namespace std;

int get_max(int a[], int n){
	int result = INT_MIN;
	for(int i = 0; i < n; i++){
		int current = 0, sum = 0;
		for(int j = i; j < n; j++){
			current += sum * a[j];
			sum += a[j];
			result = max(current, result);
		}
	}
	return result;
}

int main(){
	int n;
	cin >> n;
	int a[n];
	for(int i = 0; i < n; i++){
		cin >> a[i];
	}
	cout << get_max(a, n) << "\n";
}