#304. Sum of numbers divisible by 2
You get a positive integer n. Find the sum of all numbers from 1 to n that can be divided by 2.
### Input
One integer n (1 ≤ n ≤ 10000).
### Output
The sum.
Examples
Input
7467
Output
13939022
Input
5099
Output
6499950
💡 You can solve it with Python, JavaScript or blocks. Read the input line by line with input(). Don't print a question (like input("Number: ")). Print exactly what the output asks for, nothing more.