#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
  #include "settings/debug.cpp"
  #define _GLIBCXX_DEBUG
#else
  #define Debug(...) void(0)
#endif
#define rep(i, n) for (int i = 0; i < (n); ++i)
using ll = long long;
using ull = unsigned long long;

inline ll poww(ll x, ll n) {
  ll res = 1;
  while (n > 0) {
    if (n & 1) res *= x;
    x *= x;
    n >>= 1;
  }
  return res;
}

int main() {
  int n;
  cin >> n;
  vector<int> a(n);
  rep(i, n) cin >> a[i];
  vector<int> cnt(9, 0);
  rep(i, n) cnt[a[i]]++;
  ll ans = 0;
  for (int i = 1; i <= 8; i++) {
    for (int j = 1; j <= 8; j++) {
      ans += (ll) cnt[i] * cnt[j] * poww(i, j);
    }
  }
  cout << ans << endl;
  return 0;
}