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

int main() {
  long N, P;
  cin >> N;
  long ans = 1;
  while (cin >> P) {
    if (!P) return cout << 0 << "\n", 0;
    (ans *= P % 9) %= 9;
  }
  cout << ((ans) ? ans : 9) << "\n";
}