/* -*- coding: utf-8 -*-
 *
 * 933.cc:  No.933 おまわりさんこいつです - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

/* typedef */

typedef long long ll;

/* global variables */

/* subroutines */

inline ll dsum(ll n) {
  while (n >= 10) {
    ll sum = 0;
    while (n > 0) {
      sum += n % 10;
      n /= 10;
    }
    n = sum;
  }
  return n;
}

/* main */

int main() {
  int n;
  scanf("%d", &n);

  ll r = 1;
  for (int i = 0; i < n; i++) {
    ll pi;
    scanf("%lld", &pi);
    r *= dsum(pi);
    r = dsum(r);
  }

  printf("%lld\n", r);
  return 0;
}