Given the abstract class and two child classes below, what will be the output?

Given the abstract class and two child classes below, what will be the output?

abstract class Shape {
    abstract public function area();
}

class Square extends Shape {
    private $side;
    public function __construct($side) {
        $this->side = $side;
    }
    public function area() {
        return $this->side * $this->side;
    }
}

class Circle extends Shape {
    private $radius;
    public function __construct($radius) {
        $this->radius = $radius;
    }
    public function area() {
        return 3.14 * $this->radius * $this->radius;
    }
}

$shapes = [new Square(4), new Circle(3)];
foreach ($shapes as $shape) {
    echo $shape->area() . " ";
}