import java.util.*;

public class Main {
	public static void main (String[] args) {
    	Scanner sc = new Scanner(System.in);
    	int n = sc.nextInt();
    	double ans = 0;
    	for (int i = 1; i <= 1000000; i++) {
    	    ans += 1 / Math.pow(i, n);
    	}
    	System.out.println(ans);
	}
}