#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
using ll = long long;

int main(){
    int n; cin >> n;
    vector<int> a(n);
    for(auto &it: a) cin >> it;

    vector<int> cnt(10, 0);
    for(const auto &it: a) cnt[it]++;

    ll ans = 0;
    for(const auto &it: a){
        ll x = 1;
        for(int i = 1; i <= 8; i++){
            x *= it;
            ans += x*cnt[i];
        }
    }
    cout << ans << endl;
    return 0;
}