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

int main(){
	int n; cin >> n;
	vector<long long> v(n);
	long long p = 0, s = 0;
	for(auto&x : v) cin >> x, s += x;
	long long ans = 0, nans;
	for(auto x : v) {
		p += x*x; 
		s -= x;
		nans = p*s;
		if( nans < ans ) {
			cout << ans << endl;
			return 0;
		}
		ans = nans;
	}
}