# Circle And Chords

easy

1. You are given a number N. 2. There are 2*N points on a circle. You have to draw N non-intersecting chords on a circle. 3. You have to find the number of ways in which these chords can be drawn.

## Constraints

1 <= N <= 1000 1 <= arr[i] <= 100

## Format

### Input

A number N

### Output

Check the sample output and question video.

## Example

Sample Input

3

### Sample Output

5

Question Video