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 Python (3.4.3) (judge verdict: Accepted)

import unittest


class TestA(unittest.TestCase):
    def test_1(self):
        self.assertEqual(think(4), 48)

    def test_2(self):
        self.assertEqual(think(15), 675)

    def test_3(self):
        self.assertEqual(think(80), 19200)


def solve():
    r = read()
    result = think(r)
    write(result)


def read():
    return read_int(1)[0]


def read_int(n):
    return list(map(lambda x: int(x), read_line().split(' ')))[:n]


def read_float(n):
    return list(map(lambda x: float(x), read_line().split(' ')))[:n]


def read_line(n=0):
    if n == 0:
        return input().rstrip()
    else:
        return input().rstrip()[:n]


def think(r):
    return 3 * r ** 2


def write(result):
    print(result)


if __name__ == '__main__':
    # unittest.main()
    solve()