FibonacciNumbers

using System;
using System.Linq;

class FibonacciNumbers
{
    static void Main()
    {
        Console.Write("Length is: ");
        long n = long.Parse(Console.ReadLine());
        long firstNum = 0;
        long secondNum = 1;
        long thirdNum = 1;
        if (n == 0)
        {
            Console.WriteLine("Sorry, counting starts from 1...");
        }
        if (n == 1)
        {
            Console.WriteLine(firstNum);
        }
        else
        {
            if ( n > 2)
            {
                Console.WriteLine("{0} ", firstNum);
                Console.WriteLine("{0} ", secondNum);
                Console.WriteLine("{0} ", thirdNum);
            }
            for (int i = 0; i < n-3; i++)
            {
                firstNum = secondNum;
                secondNum = thirdNum;
                thirdNum = firstNum + secondNum;
                Console.WriteLine("{0} ", thirdNum);
            }
        }
    }
}