Sum of Natural Numbers

Given a positive integer ( N ), your task is to compute the sum of the first ( N ) natural numbers, i.e., ( S = 1 + 2 + \cdots + N ). The formula for computing ( S ) is given by:

[ S = \frac{N \times (N+1)}{2} ]

You are required to read the input from standard input (stdin) and output your result to standard output (stdout). The problem is straightforward and focuses on basic arithmetic operations.

inputFormat

The input consists of a single line containing one integer ( N ) (1 ( \leq N \leq 10^9 )), which represents the number up to which the sum of natural numbers is to be computed.

outputFormat

Output a single integer which is the sum of the first ( N ) natural numbers.## sample

5

15