static void Main(string[] args)
    {
        int[] arr = new int[] { 1, 3, 4, 2, 8, 9 };
        int[] index = new int[] { 0, 1, 2, 0, 3, 3, 2, 4, 5, 2, 5 };
        string tel = "";
        foreach (var i in index)
        {
            tel += arr[i];
        }
        Console.Write(tel);
        Console.ReadKey();
     }