using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static int NN => int.Parse(ReadLine());
    static long[] NList => ReadLine().Split().Select(long.Parse).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var n = NN;
        var p = NList;
        var ans = 1L;
        var iszero = false;
        foreach (var pi in p)
        {
            if (pi == 0) iszero = true;
            ans = ans * pi % 9;
        }
        WriteLine(iszero ? 0 : ans == 0 ? 9 : ans);
    }
}