#include <iostream>
#include <fstream>
#include <math.h>

using namespace std;

int main()
{
	const long double PHI = (1 + sqrt(5)) / 2;
	long double number;
	int n;

	ifstream in("kfib.in");
	ofstream out("kfib.out");

	in >> n;

	number = pow(PHI,n) / sqrt(5);

	if ((int(number) + 0.5) < number)
		out << int(number) + 1;
	else
		out << int(number);

	return 0;
}