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 C# (Mono 4.6.2.0) (judge verdict: Runtime Error)

using System;
using System.Linq;
using System.Text;
using System.Collections.Generic;
 
public class Hello{
    public static void Main(){
        var line = Console.ReadLine().Split(' ');
        int N = int.Parse(line[0]);
        int D = int.Parse(line[1]);
        double person = 2*D+1;
        Console.WriteLine((int)Math.Ceiling(N/person));
    }
}