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(); } }