Bit Flipper

using System;


class BitFlipper
{
    static void Main()
    {
        ulong input = ulong.Parse(Console.ReadLine());
        string bit = Convert.ToString((long)input, 2).PadLeft(64,'0');
        string result = string.Empty;

        for (int i = 0; i < bit.Length; i++)
        {
            string tempOne = bit[i].ToString();
            string tempTwo = string.Empty;
            string tempThree = string.Empty;

            if (i + 1 < bit.Length)
            {
                tempTwo = bit[i + 1].ToString();
            }
            if (i + 2 < bit.Length)
            {
               tempThree = bit[i + 2].ToString();
            }

            if (tempOne.Equals("1") && tempTwo.Equals("1") && tempThree.Equals("1"))
            {
                result += "000";
                i += 2;
                continue;
            }
            else if ((tempOne.Equals("0") && tempTwo.Equals("0") && tempThree.Equals("0")))
            {
                result += "111";
                i += 2;
                continue;
            }
            else
            {
                result += bit[i];
            }

        }
        Console.WriteLine(Convert.ToUInt64(result,2));
    }
}