JaeHyeonKim19

import java.io.*;

public class Main {
	static int fibonacci(int n) {
		if(n == 0) return 0;
		if(n == 1) return 1;
		return fibonacci(n - 1) + fibonacci(n - 2);
	}
	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		System.out.println(fibonacci(Integer.parseInt(br.readLine())));
	}
}