#include<iostream> #include<cstdio> using namespace std; const int mod=100003; long long dp[1000000]; int main() { dp[0]=dp[1]=1; dp[2] = 2; for(int i=3;i<=71;i++) { dp[i] = dp[i - 1] + dp[i - 2] + dp[i - 3]; } int n; while(scanf("%d", &n) != EOF) { if(n == 0) break; printf("%lld\n", dp[n]); } return 0; }