Choose Two

Time Limit: 1 sec

 

The Problem

There are N people in a room. You have to select any 2 people from the room. In how many ways 2 people can be selected from N people?

 

The Input

Input contains a single integer N (2≤ N ≤10⁹) per line till the end of file(EOF).

 

The Output

Print a single integer for every line of input, the answer of the problem in a separate line.

 

Sample Input

4

9

17

 

Sample Output

6

36

136

 

 

 

[School Level]

1st Online Programming Contest 2016 by Outsbook

Problem Setter: Fahim Abrar