using System;

public class Program

{

    public static void Main()

    {

        int input, first = 0, second = 1, third = 1 , forth = 0;

        Console.Write("Enter a number : ");

       input = Convert.ToInt32(Console.ReadLine());

        Console.Write("{0} {1} {2} ", first, second, third);

​

        for (int i = 4; i <= input; i++)

        {

            forth = first + second+third;

            Console.Write("{0} ", forth);

            first = second;

            second = third;

            third = forth;

        }

    }

}