Problem:
Score : 100 points

Problem Statement

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.

Constraints

1 \leq r \leq 100

r is an integer.

Input

Input is given from Standard Input in the following format:

r

Output

Print an integer representing the area of the regular dodecagon.

Sample Input 1

4

Sample Output 1

48

The area of the regular dodecagon is 3 \times 4^2 = 48.

Sample Input 2

15

Sample Output 2

675

Sample Input 3

80

Sample Output 3

19200

Solution in Ruby (2.3.3) (judge verdict: Accepted)

# 半径 a の円に内接する正十二角形の面積は 3a^2 であることが知られています。
# 整数 r が与えられるので、半径 r の円に内接する正十二角形の面積を求めて下さい。

r = gets.to_i
puts 3 * (r ** 2)