#include <bits/stdc++.h>
using namespace std;
int main() {
    int n;
    cin >> n;
    long long int A[n+1],B[n+1],C[n+1],x;
    B[0]=0;
    C[0]=0;
    for(int i = 1; i <= n; i++){
       cin >> A[i];
       B[i]=B[i-1]+A[i];
       C[i]=C[i-1]+(A[i]*A[i]);
    }
    long long int max=-1000000000;
    for(int i=1;i<n;i++)
        for(int j=i+1;j<=n;j++)
        {
            x=((B[j]-B[i-1])*(B[j]-B[i-1])-(C[j]-C[i-1]))/2;
            max=max>x?max:x;
        }
    cout <<max<< endl;
    return 0;
}