//骨牌铺方格 (找规律)
#include<iostream>
using namespace std;
int sum(int n);
long long rem[1024] = {0};
int main(){
	int n,scheme;
	cin >> n;
	while(n){
		scheme = sum(n);
		cout << scheme << endl;
		cin >> n;
	} 
	return 0;
} 

int sum(int n){
	int res = 1;
	if(rem[n]) 
		res = rem[n]; //rem[]数组用于优化递归，记忆中间结果减少重复运算
	else if(n == 1 || n ==2)
		res = n;
	else if(n==3)
		res = n + 1;	
	else
		res = sum(n - 1) + sum(n - 2) + sum(n - 3);
	return res;
}