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: Runtime Error)

import java.util.*;
 
class Main
{
    public static void main(String[] args){
    	Scanner sc = new Scanner(System.in);
		int[] points = new int[2];
		for(int i=0; i<points.length; i++){
			points[i] = sc.nextInt();
		}
		
		int intN = points[0];
		int intD = points[1];
		
        System.out.println((int)Math.ceil((intN / (intD*2+1))));
    }
}