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 Go (1.6) (judge verdict: Accepted)

package main

import "fmt"

const (
	maxBufferSize     = 2000000 // check
	initialBufferSize = 20000
)

func solve() {
	var r int64
	fmt.Scan(&r)

	ans := 3 * r * r

	fmt.Println(ans)
}

func main() {
	solve()
}