import java.util.*;public class ACMmuniu?{ public static void main(String[] args)? { Scanner sc=new Scanner(System.in); while(sc.hasNextInt()) { int n=sc.nextInt(); if(n==0) { break; } int a=1,b=2,c=3,sum=1,m; if(n==1) { System.out.println(a); } else if(n==2) { System.out.println(b); } else if(n==3) { System.out.println(c); } else { sum=3; m=1; for(int i=4;i<=n;i++) { if(m<=3) { if(m==1) { sum+=a; a=sum; } else if(m==2) { sum+=b; b=sum; } else if(m==3) { sum+=c; c=sum; } m++; } if(m==4) { m=1; } } System.out.println(sum); } } }}