#include<bits/stdc++.h>
using namespace std;
long long h[5005];int c[5005],a[5005],b[5005],n;
int jia(long long x,long long y){int cnt=1,ans=1;
	while(x!=0){a[cnt]=x%10;x/=10;cnt++;}while(y!=0){b[ans]=y%10;y/=10;ans++;}
	int maxx;
	if(cnt>ans)maxx=cnt+1;else maxx=ans+1;
	for(int i=1;i<=maxx;i++){c[i]+=a[i]+b[i];c[i+1]+=c[i]/10;c[i]%=10;}
	long long sum=0,chengshu=1;
	for(int i=1;i<=maxx;i++){sum+=chengshu*c[i];chengshu*=10;}
	return sum;}
int main(){
	cin>>n;
	h[1]=1;h[2]=1;
	for(int i=3;i<=n;i++){h[i]=jia(h[i-1],h[i-2]);}
	cout<<h[n];
	return 0;}