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

using ll = long long;

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int n;
    cin >> n;

    ll k{ 1 };
    bool f{ false };
    for (int i = 0; i < n; ++i)
    {
        ll p;
        cin >> p;

        if (p == 0)
        {
            f = true;
            k = 0;
            break;
        }

        k *= p % 9;
        k %= 9;
    }

    if (k == 0)
        k = f ? 0: 9;
    cout << k << "\n";

    return 0;
}