Count Of Valleys And Mountains

easy

1. You are given a number n, representing the number of upstrokes / and number of downstrokes .
2. You are required to find the number of valleys and mountains you can create using strokes.
E.g.

<img src="http://pepcoding.com/resources/ojquestionresource/images/countvalleys2.JPG" alt="countvalleys">

Note -> At no point should we go below the sea-level. (number of downstrokes should never be more than number of upstrokes).

Input Format

A number n

Output Format

A number representing the number of valleys and mountains you can create using strokes.

Constraints

0 <= n <= 15

Notice

Try First, Check Solution later

1. You should first read the question and watch the question video.
2. Think of a solution approach, then try and submit the question on editor tab.
3. We strongly advise you to watch the solution video for prescribed approach.

Example

Input

Output

Number Of Bsts

Count Brackets