#include<bits/stdc++.h>
using namespace std;
long long a[1110]={1,1,2,4,7,11};
int main()
{
    int n;
    while(cin>>n,n)
    {
        if(n==1) 
        {
            cout<<1<<endl;
            continue;
        }
        if(n==2)
        {
            cout<<2<<endl;
            continue;
        }
        if(n==3)
        {
            cout<<4<<endl;
            continue;
        }
        for(int i=3;i<=n;i++)
        {
            a[i]=a[i-1]+a[i-2]+a[i-3];
        }
        cout<<a[n]<<endl;
    }
    return 0;
}