Untitled

#include <iostream>
#include <fstream>
#include <iomanip>
#include <cmath>
#include <vector>
int recurtion(int a) {
	
	if (a > 0) return recurtion(a - 1) + recurtion(a - 2);
	else return 1;
}
using namespace std;

int main(){
	int a;
	cin >> a;
	std::cout << recurtion(a);
}