#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; }