#include <algorithm>
#include <stdio.h>
#define  maxn	   200003
using	 namespace std;
typedef  long long LL;

int n;
LL ans;
int a[maxn];
LL sum[maxn];

int main() {
	
	scanf( "%d" , &n );
	for( int i = 1 ; i <= n ; i++ ) {
		scanf( "%d" , &a[i] );
		sum[i] = sum[i-1] + a[i];
	}
	
	for( int i = 1 ; i <= n ; i++ ) {
		LL tot = 0;
		for( int j = i + 1 ; j <= n ; j++ ) {
			tot += a[j] * ( sum[j-1] - sum[i-1] );
			ans = max( ans , tot );
		}
	}
	
	printf( "%lld\n" , ans );
	
}