#include <fstream>
#include <cstring>
using namespace std;
#define dim 230
int a[dim], b[dim];


void adun(int A[], int B[])
{
	int i, t=0;
	for(i=1;i<=A[0] || i<=B[0] || t;++i,t/=10)
		A[i]=(t+=A[i]+B[i])%10;
	A[0]=i-1;
}

int main()
{
	ifstream fin("nunta.in");
	ofstream fout("nunta.out");
	int n, i;
	int aux[dim];
	a[1]=b[1]=a[0]=b[0]=1;
	fin>>n;
	
	for(i=3;i<=n+1;++i)
	{
		memcpy(aux,b,sizeof(b));
		adun(b,a);
		memcpy(a,aux,sizeof(b));
	}
	
	for(i=b[0];i;--i)
		fout<<b[i];
	
	return 0;
}