#include<stdio.h>
int main()
{
int i,n,a[100];
while(scanf("%d",&n)!=EOF)
{
a[1]=1;a[2]=2;a[3]=3;
if(n==0)break;
if(n>=4)
{
for(i=4;i<=n;i++)
{
a[i]=a[i-1]+a[i-3];
}
printf("%d\n",a[n]);
}
else if(n>=3) printf("%d\n",a[n]);
else if(n>=2) printf("%d\n",a[n]);
else if(n>=1) printf("%d\n",a[n]);
}
return 0;
}