<?php
interface create
{
    function F1();
    function F2();
}

class Rectangle implements create
{
    private $a;
    private $b;

    function __construct($a, $b) {
        $this->a = $a;
        $this->b = $b;
    }

    public function F1() { //perimeter
        $a = $this->a;
        $b = $this->b;
        $p = 2 * $a * $b;
        return $p;
    }
    public function F2() {//lice
        return ($this->a * $this->b);
    }
}

class Box implements create
{
    private $a;
    private $b;
    private $c;

    function __construct($a, $b, $c) {
        $this->a = $a;
        $this->b = $b;
        $this->c = $c;
    }

    public function F1() { //lice
        $a = $this->a;
        $b = $this->b;
        $c = $this->c;
        $s = 2 * ($a * $b + $a * $c + $b * $c);
        return $s;
    }
    public function F2() { //nishto
        return 0;
    }
}

$rect = new Rectangle(3, 6);
echo $rect->F1();
echo "<br>";
echo $rect->F2();
echo "<br>";
$box = new Box(2, 3, 4);
echo $box->F1();
echo "<br>";
echo $box->F2();
?>