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++14 (GCC 5.4.1) (judge verdict: Accepted)

#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <vector>
#include <queue>
#include <iostream>
#include <set>
#include <map>
#include <string>
#include <algorithm>

using namespace std;

typedef long long int ll;
typedef pair<int, int> Pii;
typedef pair<int, double> Pid;
typedef pair<double, int> Pdi;
typedef pair<double, double> Pdd;
typedef pair<ll, ll> P;
typedef pair<P, ll> PP;

const ll mod = 1e9+7;
const ll INF = 2e9;
const double epsilon = 1e-7;
const double PI = 3.1415926535;



int main(void){
    ll r; cin >> r;
    cout << 3 * r * r << endl;
	return 0;
}