Kattis

# A Real Challenge

Cow image from Pixabay
Old MacDonald had a farm, and on that farm she had a square-shaped pasture, and on that pasture she had a cow that was prone to escape. So now Old MacDonald wants to set up a fence around the pasture. Given the area of the pasture, how long a fence does Old MacDonald need to buy?

## Input

The input consists of a single integer $a$ ($1 \le a \le 10^{18}$), the area in square meters of Old MacDonald’s pasture.

## Output

Output the total length of fence needed for the pasture, in meters. The length should be accurate to an absolute or relative error of at most $10^{-6}$.

Sample Input 1 Sample Output 1
16

16

Sample Input 2 Sample Output 2
5

8.94427190999915878564