A circle is drawn with center at ~O~ and ~N~ points ~p_1~ through ~p_N~ are equally spaced around the circle.

Line segments are drawn to connect ~O~ to each of these ~N~ points.

Compute the number of ways to delete ~N~ of the line segments or arcs such that the ~N+1~ points are still connected.

Constraints

~1 \le N \le 100~

In test data worth 10% of marks, you may assume ~N \le 10~.

Input Specification

The first and only line contains a single positive integer, ~N~.

Output Specification

Output the number of desired configurations.

Sample Input

3

Sample Output

16