#include<fstream>

using namespace std;

long long sirul(long long n)
{
if(n==1) return 1;
else if(n==2) return 1;
else return sirul(n-1)+sirul(n-2);}

int main()
{
    ifstream cin ("kfib.in");
    ofstream cout ("kfib.out");
	long long n;
	cin>>n;
	cout<<sirul(n);
	cin.close();
	cout.close();
	return 0;
}