import java.util.*;

public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();
    double p1 = 1;
    double p2 = 1;
    double p3 = 1;
    double p4 = 1;
    double p5 = 1;
    for(int i = 0; i < n; i++) {
      p1 = p1 * ((double)1 / (double)6);
      p2 = p2 * ((double)2 / (double)6);
      p3 = p3 * ((double)3 / (double)6);
      p4 = p4 * ((double)4 / (double)6);
      p5 = p5 * ((double)5 / (double)6);
    }
    double ans = 1 - p5 * (double)6 + p4 * (double)15 - p3 * (double)20 + p2 * (double)15 - p1 * (double)6;
    System.out.println(ans);
  }
}