#include<cstdio>
#include<vector>


using namespace std;
using ll=long long int;


ll solve(int n)
{
	vector<ll> f;

	f.resize(n+1);
	f[0]=f[1]=1;
	for(int i=2;i<=n;i++)
	{
		f[i]=f[i-1]+f[i-2];
	}
	return f[n];
}


int main(void)
{
	int n;

	while(scanf("%d", &n)==1)
	{
		printf("%lld\n", solve(n));
	}

	return 0;
}