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 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include<stdio.h>

int main() {
	int  n, a[200000];
	

	scanf("%d", &n);
	for (int  i = 0; i < n; i++) {
		scanf("%d", &a[i]);
	}
	int sum = 0;

	for (int i = 0; i < n/2; i++) {
		for (int j = i; j < n; j = j + i+1) {

			sum = sum + a[j];

		}
		if (sum % 2 != a[i]) {
			a[i] = 1;
		}
	}

	int count = 0;

	for (int i = 0; i < n; i++) {
		if (a[i] == 1) {
			count++;
		}
	}

	printf("%d\n", count);
	int count2 = 0;
	for (int i = 0; i < n; i++) {
		if (a[i] == 1) {
			count2++;
			if (count2 != count) {
				printf("%d ", a[i]);
			}
			else {
				printf("%d\n", a[i]);
				break;
			}
		}
	}
	return 0;
}