Question

Diagonal Tally Path Enumeration

2

2

As here in the image, we can see that there are 2 available options of going from bottom-left to top-right.

Given an n × n grid with the top-left corner indexed as (0, 0), a Diag Tally is defined as a staircase walk from the bottom-left corner (n−1, 0) to the top-right corner (0, n−1) while remaining above the diagonal cells (or cells on the line from the bottom-left to the top-right). The task is to enumerate the number of Diag Tally paths from (n−1, 0) to (0, n−1).

**Note:****Staircase walk:**A walk that only allows upward or rightward movements, resembling the steps of a staircase.**Diagonal cells:**The cells that lie along the line from the bottom-left corner to the top-right corner of the grid.Input

The first and only line of the input contains a single integer n, denoting the dimension of the grid.

1 ≤ N ≤ 30

**Constraints**1 ≤ N ≤ 30

Output

Print the number of Diag Tally paths from (n−1, 0) to (0, n−1).

**Note**: The answer can we very large, so use appropriate datatype.Example

**Sample Input**

2

**Sample Output**

2

**Explanation**

As here in the image, we can see that there are 2 available options of going from bottom-left to top-right.