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 <iostream>
#include <string> 
#include <vector> 
#include <algorithm> 
#include <utility> 
#include <tuple> 
#include <cstdint> 
#include <cstdio> 
#include <map> 
#include <queue> 
#include <set> 
#include <stack> 
#include <deque> 
#include <unordered_map> 
#include <unordered_set> 
#include <bitset> 
#include <cctype> 
#include<math.h>
using namespace std;

//#define int long long
//#define endl "\n"
#define m_p make_pair
#define mod 1000000007
#define all(v)  v.begin(),v.end()
#define rep(i,n)  for(int i=0; i<(int) (n); i++)
#define all(v)  v.begin(),v.end()
#define vecin(v) for(int i=0; i<(int)v.size(); i++)cin>>v[i];
using namespace std;

int jousu(int, int);
int jousu(int x00, int y00) {
	int z00 = 1;
	for (int i = 0; i < y00; i++) {
		z00 *= x00;
	}
	return z00;
}
int keta(int x00) {
	int z00 = x00;
	int w00 = 0;
	while (z00 != 0) {
		z00 /= 10;
		w00++;
	}
	return w00;
}




int main() {
	int r;
	cin >> r;
	cout << r * r * 3 << endl;
}