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)

"""
# 標準入力取得
## 文字列
 = sys.stdin.readline().rstrip()
 = list(sys.stdin.readline().rstrip())

## 数値
 = int(sys.stdin.readline())
 = map(int, sys.stdin.readline().split())
 = list(map(int, sys.stdin.readline().split()))
 = [list(map(int,list(sys.stdin.readline().split()))) for i in range(h)]  # 二次元配列入力　二次元マップみたいな入力のとき

# 0埋め, 小数点出力桁指定時のときの出力
a = 100
b = 0.987654321
print("{0:06d}-{1:6f}".format(a,b))
000100-0.987654

# 文字列をリストに格納
char_list = list("abcd") # ["a","b","c","d"]
"""

import math
import sys
import itertools
import queue
from fractions import gcd

def lcm(a, b):
    return a * b // gcd(a, b)

mod = 1000000007

if __name__ == "__main__":
    r = int(sys.stdin.readline())
    print(3 * (r ** 2))