Sum of even numbers from 1 to N

Rust Easy loops

Task «Sum of even numbers from 1 to N»

Write a program that reads a positive integer N (N ≥ 1) from the keyboard and outputs the sum of all even numbers from 1 to N inclusive. Use a loop to iterate through the numbers.

Input Format

One integer N (1 ≤ N ≤ 1000).

Output Format

One integer — the sum of even numbers from 1 to N.

Examples

Example 1

INPUT

10

OUTPUT

30

Example 2

INPUT

1

OUTPUT

0

main.rs