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

using ll = long long;

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