#include <iostream>
#include <fstream>
#include <iomanip>
#include <vector>
#include <algorithm>
#include <cmath>
#include <unordered_map>
#include <map>
#include <queue>
#include <string>
#include <set>
#include <list>
#include <climits>
#include <bitset>
#include <numeric>
#include <cassert>
#include <regex>
using std::cout;
using std::cin;
using std::string;
using std::vector;

int main()
{
    int n;
    cin >> n;
    std::map<int, int> count;
    for (int i = 0; i < n; i++)
    {
        int a;
        cin >> a;
        count[a]++;
    }
    long long ans = 0;
    for (int i = 1; i <= 8; i++)
    {
        for (int j = 1; j <= 8; j++)
        {
            ans += (long long)pow(i, j) * count[i] * count[j];
        }
    }
    cout << ans;
}