#include<stdio.h> int numb(int n) { int arr[1000] = { 0 }; arr[1] = 1; arr[2] = 2; arr[3] = 3; arr[4] = 4; int i = 4; for (i = 4; i <= n; i++) { arr[i] = arr[i - 1] + arr[i - 3]; } int m = n; if (m <= 4) { return arr[m]; } else { return arr[i-1]; }

}

int main() { int n; while (scanf("%d", &n) &&n!=0) { printf("%d\n", numb(n)); } return 0; }