#include <ctype.h>
#include <stdio.h>
int main(void)
{
int n, i;
int fab[55] = {1, 2, 3, 4, 6};
for (i = 5 ; i < 55 ; i++)
fab[i] = fab[i - 1] + fab[i - 3];
while (scanf("%d", &n), n)
printf("%d\n", fab[n - 1]);
}
return 0;