#include <iostream>
using namespace std;
int main(void) {
	long long n, p;
	cin >> n;
	long long ans = 1;
	for (int i = 0; i < n; ++i) {
		cin >> p;
		if (p == 0) {
			cout << 0 << endl;
			exit(0);
		}
		ans = ans * p % 9;
	}
	if (ans == 0) ans = 9;
	cout << ans << endl;
	return 0;
}