import java.io.PrintWriter;
import java.util.Arrays;
import java.util.Scanner;
import java.util.Stack;

class Main {
	public static void main(String[] $) {
		new Main().run();
	}
	
	void run() {
		Scanner sc=new Scanner(System.in);
		int N=sc.nextInt();
		double ans=0;
		for (double i=1;i<1e5;++i) {
			ans+=Math.pow(1/i, N);
		}
		System.out.println(ans);
		
	}
	
	void tr(Object...objects) {System.out.println(Arrays.deepToString(objects));}
}