Easy Peasy Arithmetic

Bored of going through the beginner problemset, Timmy decided to take on a little challenge before he goes to sleep.

Given the set of all square integers ~\{1, 4, 9, 16, 25, ...\}~ and an integer ~n~, he wants to determine how many integers in the set are strictly less than ~n~.

Input

The input consists of one integer ~n\ (1 \leq n \leq 10^{18})~.

Output

Output the number of square integers in the infinite set that are strictly less than ~n~.

Examples

Input 1

1

Output 1

0

Input 2

5

Output 2

2