using System;

public class Caw

{

    public static void Main()

    {

        while(Application()){}

    }

    static bool Application(){

        Console.WriteLine("Input the number of year.");

        int numOfYear = getInput();

        if(numOfYear == 0)

            return false;

        int oneYear = 0;

        int twoYear = 0;

        int threeYear = 0;

        int overFour = 1;

        for(int i=1; i<numOfYear; i++){

            overFour += threeYear;

            threeYear = twoYear;

            twoYear = oneYear;

            oneYear = overFour;

        }

        int sum = oneYear + twoYear + threeYear + overFour;

        Console.WriteLine("the number of caw in year {0} is {1}", numOfYear, sum);

        return true;

    }

    static int getInput(){

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

        while(input < 0 || input >= 55){

            Console.WriteLine("the number n should be 0<n<55. (Input 0 to quit.)");

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

        }

        return input;

    }

}