#include "bits/stdc++.h"
using namespace std;
typedef long long int ll;
typedef vector<ll> vl;
typedef pair<ll, ll> PP;
#define rep(i,n) for(ll i = 0; i < ll(n); i++)
#define all(v) v.begin() , v.end()
#define inputv(v,n) rep(i,n){\
    ll x;\
    cin>>x;\
    v.push_back(x);\
    }
const ll INF = 999999999999999;
const ll MOD = 1000000007;
ll a, b, c, d, e, f, p, t, x, y, z, q, m, n, r, h, k, w, l, ans = 0;
int main() {
	cin >> n;
	k = 1;
	ans = 1;
	rep(i, n) {
		cin >> a;
		if (a == 0)k = 0;
		ans = (ans * a) % 9;
	}
	if (ans == 0 && k == 1)cout << 9 << endl;
	else if (ans == 0)cout << 0 << endl;
	else cout << ans << endl;
}