#include <bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;

using ll = int64_t;
using ul = uint64_t;
using ld = long double;
using vi = vector<int>;
using vd = vector<double>;
using vc = vector<char>;
using vs = vector<string>;
using vb = vector<bool>;
using vl = vector<ll>;
using vvi = vector<vi>;
using vvd = vector<vd>;
using vvc = vector<vc>;
using vvb = vector<vb>;
using vvl = vector<vl>;
using mint = modint998244353;
using vm = vector<mint>;

int main() {
  int N;
  cin >> N;
  vl A(N);
  for (int i = 0; i < N; i++) {
    cin >> A[i];
  }
  sort(A.begin(), A.end());
  ll ans = 0;
  for (int i = 1; i < N; i++) {
    ans += A[i]*A[i - 1];
    A[i] += A[i - 1];
  }
  cout << ans << endl;
  return 0;
}