#include<bits/stdc++.h>
using namespace std;
using LL = long long;
using ULL = unsigned long long;
#define rep(i,n) for(int i=0; i<(n); i++)

int main() {
	int N; cin >> N;
	LL K = 1;
	rep(i, N) {
		LL A; cin >> A;
		if (A == 0) { cout << 0 << endl; return 0; }
		K = K * (A % 9) % 9;
	}
	if (K == 0) K = 9;
	cout << K << endl;

	return 0;
}