hdu 2018

import java.util.Scanner;/** * 母牛的故事 * */public class Main{public static void main(String[] args) {Scanner in=new Scanner(System.in);while(in.hasNext()) {int n=in.nextInt();if(n==0) continue;System.out.println(cow(n));}}public static int cow(int n) {if(n<=4) {return n;} else {return cow(n-1)+cow(n-3);}}}