#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <cstring>
#include <cstdlib>
#include <cmath>
using namespace std;
using ll = long long;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);

    int n;
    cin >> n;

    ll r = 1;
    for (int i = 0; i < n; i++) {
        ll p;
        cin >> p;

        if (p == 0) {
            cout << 0 << endl;
            exit(0);
        }
        r = r * p % 9;
    }

    if (r == 0) r = 9;
    cout << r << endl;

    return 0;
}