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: Accepted)

using System;
using System.Linq;

namespace atcoder
{
    class Program
    {
        static void Main(string[] args)
        {
            A.Dodecagon();
        }
    }

    class A
    {
        public static void Dodecagon()
        {
            int r = Input.getInt();
            int d = 3 * r * r ;
            Output.writeInt(d);   
        }


    }
  
    class Input
    {
        public static int getInt()
        {
            int i = int.Parse(Console.ReadLine());
            return i;
        }

        public static string getString()
        {
            string s = Console.ReadLine();
            return s;
        }
        public static int[] getIntArray()
        {
            string[] s = Console.ReadLine().Split(' ');
            int[] num = s.Select(x=>int.Parse(x)).ToArray();
            return num;
        }
    }

    class Output
    {
        public static void writeInt(int i)
        {
            Console.WriteLine(i);
        }
    }
}