Accenture OA-27 2024

Problem Description

Mr. Professor is a great scientist, but he is not able to find a solution to one problem. There are N straight lines that are not parallel, and no three lines go through the same point. The lines divide the plane into M regions. Write a function to find out the maximum number of such regions he can get on the plane.

Input Format:

• The input consists of a single integer N representing the number of straight lines.

Output Format:

Output the maximum number of regions that can be formed by these lines.

Constraints:

• 1 ≤ N ≤ 10^9

Example

Sample Input:

3

Sample Output:

7

Explanation:
With 3 lines, the maximum number of regions that can be formed is 7.