using System;

public class hello
{
    public static int[] a;
    public static int n;
    static void Main()
    {
        n = int.Parse(Console.ReadLine().Trim());
        string[] line = Console.ReadLine().Trim().Split(' ');
         a = Array.ConvertAll(line, int.Parse);
        getAns();
    }
    static int  getNext ( int p , int pre )
    {
        var t = pre * 100 + a[p] * 10 + a[p + 1];
        if (t == 12 | t == 120 | t == 201) return 1;
        else if (t == 21 | t == 102 | t == 210) return 2;
        return 0;
    }
    static void getAns ()
    {
        var pre = getNext(1, a[0]);
        for (int i = 1; i < n; i++)
        {
            var w = getNext(2 * i + 1, pre);
            pre = w;
        }
        Console.WriteLine(pre);
    }
}