12459

#include <iostream>
#include <cstdio>
#include <cstdio>
#include <cstring>
#include <vector>
#include <cmath>
#include <cstdlib>
#include <fstream>

#define INF 1000000
#define ll long long

using namespace std;

struct node{
ll female,male,sum;
};
int main()
{

	node fib[85];
	fib[1].female=0;
	fib[1].male=1;
	fib[1].sum=1;

	fib[2].female=1;
	fib[2].male=1;
	fib[2].sum=2;

	for(int i=3;i<85;i++)
	{
		fib[i].female=fib[i-1].sum;
		fib[i].male=fib[i-1].female;
		fib[i].sum=fib[i].male+fib[i].female;
	}
	int n;
	while(scanf("%d",&n))
	{
		if(n==0)
		break;
		printf("%lld\n",fib[n].sum);
	}
	return 0;
}