Decimal To Binary

using System;

class DecimalToBinary
{
    static void Main(string[] args)
    {
        long userNum = long.Parse(Console.ReadLine());
        bool checkFirstBit = false;
        string result = "";
        for (int bit = 63; bit >= 0; bit--)
        {
            if (!checkFirstBit && (((userNum >> bit) & 1) != 1))
            {
                continue;
            }
            else
            {
                checkFirstBit = true;
                result += ((userNum >> bit) & 1).ToString();
            }
        }
        Console.WriteLine(result.Length == 0 ? "0" : result);
    }
}