#pragma GCC optimize ("O3")
#include <bits/stdc++.h>
using namespace std;
const long long nmax = 1e6 + 5;
long long a[nmax], n, mx = 0;
int main(){
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);cout.tie(NULL);
  cin >> n;
  for (long long i = 1; i <= n; ++i) cin >> a[i];
  for (long long i = 1; i <= n; ++i)
  {
    for (long long j = i + 1; j <= n; ++j)
    {
      mx = max(mx, a[i] * a[i] + a[j] * a[j]);
    }
  }
  cout << mx;
}