Fibonacci Numbers

using System;
using System.Text;

class SquareofStars
{
    static void Main(string[] args)
    {
        //Problem 10.* Fibonacci Numbers

        int n = int.Parse(Console.ReadLine());
        if (n == 0)
        {
            Console.WriteLine("Invalid input");
        }
        else if (n == 1)
        {
            Console.WriteLine(0);
            return;
        }

        int x1 = 0;
        int x2 = 1;
        Console.Write("{0} {1} ", x1, x2);
        int x3;

        for (int i = 2; i <= n; i++)
        {

            x3 = x1 + x2;
            if (i!=n)
            {
                Console.Write(" {0},", x3);

            }
            else if (i==n)
            {
                Console.Write(" {0}", x3);

            }

            x1 = x2;
            x2 = x3;
        }

        Console.WriteLine();


    }
}