import java.util.*;
import java.io.*;
import java.math.*;
public class Main {
    public static void main(String[]args){
		Scanner sc = new Scanner(System.in);
		PrintWriter ou = new PrintWriter(System.out);
		int n = sc.nextInt();
		if(n == 0) ou.println("1.644934066848226436472");
		else{
			double yono = 0;
			for(int i = 1 ; i <= n ; i++){
				yono += 1.0 / i;
			}
			yono /= n;
			ou.println(yono);
		}
		ou.flush();
	}
}