#include<iostream>
#include<stdio.h>
using namespace std;

int f[6000000]

int main()
{ int i,n;

 freopen("kfib.in", "r", stdin);
 freopen("kfib.out", "w", stdout);

 cin>>n;

 f[1]=f[2]=1;

 for(i=3;i<=n;i++)
	 f[i]=f[i-1]+f[i-2];


 cout<<f[n];

}