题目描述
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-----
4
-----Sample Output-----
48
The area of the regular dodecagon is $3 \times 4^2 = 48$.
输入格式
见题面
输出格式
见题面
样例输入
4
样例输出
48