#include <iostream>
#include <vector>
using namespace std;

int main(){
	int n; cin >> n;
	vector<long long> v(n);
	for(auto&x : v) cin >> x;
	long long ans = 0;
	for(int k = 1; k < n; ++k){
		long long p = 0, s = 0;
		for(int i = 0; i < k; ++i) p += v[i] * v[i];
		for(int i = k; i < n; ++i) s += v[i];
		ans = max(ans, p*s);
	}
	cout << ans << endl;
}