#include <bits/stdc++.h>
using namespace std;
using ll = long long;

int main() {
    int n;cin >>n;
    vector<ll> p(n);
    ll mult =1;
    for(int i=0;i<n;i++){
        cin >> p[i];
        if(p[i]==0){
            cout << 0 << endl;
            return 0;
        }else{
        mult=(p[i]%9)*(mult%9);
        }
    }
    if(mult%9==0){
        cout << 9 << endl;
    }else{
        cout << mult%9 << endl;
    }
    
    return 0;
}