Score : 100 points
It is known that the area of a regular dodecagon inscribed in a circle of radius a is 3a^2.
Given an integer r, find the area of a regular dodecagon inscribed in a circle of radius r.
Input is given from Standard Input in the following format:
r
Print an integer representing the area of the regular dodecagon.
4
48
The area of the regular dodecagon is 3 \times 4^2 = 48.
15
675
80
19200