#include<set>
#include<string> 
#include<cstring>
#include<algorithm>
using namespace std;
const int N=1e6+10;
const int INF=0x3f3f3f3f;
int n,k,a[N];
void f() { 
	a[1]=1,a[2]=2; 
	for(int i=3;i<=50;i++) 
	a[i]=a[i-1]+a[i-2]; 
} 
int main(){ 
	f(); 
	while(cin>>k)
	{ 
	if(k==0) break; 
	else cout<<a[k]<<endl; 
	} 
	return 0;
}