baekjoon 10870

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;

class Main{
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringBuilder sb = new StringBuilder();
        int N = Integer.parseInt(br.readLine()), M=1;
        M = fibonacci(N);
        sb.append(M);
        System.out.println(sb);
        br.close();
    }

    public static int fibonacci(int n){
        if (n==1){
            return 1;
        } else if (n==0){
            return 0;
        }
        else {
            return fibonacci(n - 1) + fibonacci(n - 2);
        }
    }
}