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 OCaml (4.10.0) (judge verdict: Accepted)

(* Vicfred
 * https://atcoder.jp/contests/abc134/tasks/abc134_a
 * math, implementation
 * *)
Scanf.scanf "%d\n" @@ fun r ->
    Printf.printf "%d\n" @@
    3 * r * r