import java.util.Scanner;
public class Main{
    public static void main(String args[]){
        Scanner in = new Scanner(System.in);
        while(in.hasNext()){
            int month = in.nextInt();
            int sum=getAll(month);
            System.out.println(sum);
        }
    }
    public static int getAll(int m){
        if(m==1 || m==2){
            return 1;
        }else{
            return getAll(m-1)+getAll(m-2);
        }

    }
}