#include<iostream>
using namespace std;
typedef long long ll;

int main(){
    int n;
    cin >> n;
    ll p = 1;
    for(int i = 0; i < n; i++){
        ll x;   cin >> x;
        if(x == 0){
            cout << 0 << endl;
            return 0;
        }
        p = p*x%9;
    }
    cout << (p%9==0 ? 9 : p) << endl;
    return 0;
}