#355. Loop: the sum of the even numbers up to n
You get a positive integer n. Use a `for` loop to find **the sum of the even numbers up to n**.
### Input
One integer n (1 ≤ n ≤ 20).
### Output
One integer.
Examples
Input
19
Output
90
Input
14
Output
56
💡 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.