九度 1205

#include <cstdio>
#include <iostream>
using namespace std;

#ifdef ONLINE_JUDGE                                   
#define FINPUT(file)  0
#define FOUTPUT(file) 0
#else                                                
#define FINPUT(file)  freopen(file,"r",stdin)
#define FOUTPUT(file) freopen(file,"w",stdout)
#endif


int main()
{
    FINPUT("in.txt");
    FOUTPUT("out.txt");
    
    int n;
    while(cin>>n && n)
    {
		long long int f1 = 1;
		long long int f2 = 2;
		long long int f3 = 3;
		int i = 4;
		while(i<=n)
		{
			f1 = f2;
			f2 = f3;
			f3 = f1+f2;
			
			i++; 
		} 
		if(n==1)
			cout<<f1<<endl;
		else if(n==2)
			cout<<f2<<endl;
		else if(n>=3)
			cout<<f3<<endl;
    }
    return 0;
}