#include <bits/stdc++.h>
#define rep(i,n) for(int (i)=0;(i)<(n);(i)++)
typedef long long ll;
using namespace std;
 
int main()
{
  ios::sync_with_stdio(0);
  cin.tie(0);
  ll n;
  cin >> n;
  vector<ll> p(n);
  ll sum=1;
  rep(i,n){
    cin >>p[i];
    sum *= p[i];
  }
  if(sum==0){
    cout << 0 << endl;
  }else if(sum%9==0){
  cout << 9 << endl;
  }else{
    cout << sum%9 << endl;
  }
  return 0;
}