#include <bits/stdc++.h>
// #include <atcoder/modint>
#define rng(a) a.begin(),a.end()
#define rrng(a) a.rbegin(),a.rend()
#define INF 2000000000000000000
#define ll long long
#define ld long double
#define pll pair<ll, ll>
using namespace std;
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }

int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  ll N;
  cin >> N;
  vector<ll> A(N);
  for (ll i = 0; i < N; ++i) {
    cin >> A.at(i);
  }
  sort(rng(A));
  ll ans = 0;
  for (ll i = 1; i < N; ++i) {
    ans += i * (N - i) * (A.at(i) - A.at(i - 1));
  }
  cout << ans << "\n";
}

#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < int(n); i++)
using namespace std;
using ll = long long;
using P = pair<int, int>;

int main() {
  int n;
  cin >> n;
  vector<ll> a(200);
  rep(i, n) {
    int x;
    cin >> x;
    a[x % 200]++;
  }

  ll ans = 0;
  rep(i, 200) ans += a[i] * (a[i] - 1) / 2;
  cout << ans << endl;
}