#pragma GCC optimize ("O3")
#pragma GCC target ("avx")
#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define rep(i, n) for(int i = 0; i < (n); i++)
#define rep1(i, n) for(int i = 1; i <= (n); i++)
#define co(x) cout << (x) << "\n"
#define cosp(x) cout << (x) << " "
#define ce(x) cerr << (x) << "\n"
#define cesp(x) cerr << (x) << " "
#define pb push_back
#define mp make_pair
#define chmin(x, y) x = min(x, y)
#define chmax(x, y) x = max(x, y)
#define Would
#define you
#define please


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


	int N;
	cin >> N;

	int mod = 9;
	unsigned long long k = 1;
	int zero = 0;
	rep(i, N) {
		ll a;
		cin >> a;
		if (a == 0) zero = 1;
		k *= a;
		k %= mod;
	}

	if (zero) co(0);
	else if (k) co(k);
	else co(9);

	Would you please return 0;
}