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 Java8 (OpenJDK 1.8.0) (judge verdict: Wrong Answer)

import java.util.Scanner;

public class Main {
  public static void main(String[] args) {
    int radius;
    Scanner scanner = new Scanner(System.in);
    System.out.println("整数の値を入力してください");
    while(true) {
        radius = scanner.nextInt();
        
        if(1<=radius && radius<=100) {
          break;
        } else {
          System.out.println("半径の値を1～100の範囲で入力してください");
        }
    }
    double area = Math.pow(3*radius, 2);
    System.out.println("求める面積の値は" + area + "です");
  }
}