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 PHP7 (7.0.15) (judge verdict: Wrong Answer)

<?php
fscanf(STDIN, "%d", $n);
$l = [];
for ($i=0; $i < $n; $i++) {
    fscanf(STDIN, "%d", $a);
    list($max, $index) = get_smaller_max($a, $l);
    if ($max === -1) {
        $l[] = $a;
    } else {
        $l[$index] = $a;
    }
}
echo count($l);

function get_smaller_max($a, $l) {
    $max = -1; $index = -1;
    $c = count($l);
    for ($i=0; $i < $c; $i++) {
        if ($l[$i] < $a && $l[$i] > $max) {
            $max = $l[$i];
            $index = $i;
        }
    }
    return [$max, $index];
}
?>