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;

class Program
{
    static void Main(string[] args) {
        var ret = process(new System.IO.StreamReader(Console.OpenStandardInput()));
        //var ret = process("4");

        Console.WriteLine(ret);
        //Console.ReadLine();
    }

    static string process(string input) {
        return process(new System.IO.StringReader(input));
    }

    static string process(System.IO.TextReader input) {
        int a  = int.Parse(input.ReadLine());
        
        return (3*a*a).ToString();
    }
}