abstract class Calculator
{
 private $number1;
 private $number2;
 public $result;
 /**
  * @return the $number2
  */
 public function getNumber2() {
  return $this->number2;
 }
 /**
  * @param field_type $number2
  */
 public function setNumber2($number2) {
  $this->number2 = $number2;
 }
 /**
  * @return the $number1
  */
 public function getNumber1() {
  return $this->number1;
 }
 /**
  * @param field_type $number1
  */
 public function setNumber1($number1) {
  $this->number1 = $number1;
 }
 abstract function get_result();
 }
class Add extends Calculator
{
  public function get_result($number1,$number2)
  {
   return $number1+$number2;
  }
}
class Sub extends Calculator
{
  public function get_result($number1,$number2)
  {
   return $number1-$number2;
  }
}
class Mul extends Calculator
{
  public function get_result($number1,$number2)
  {
   return $number1*$number2;
  }
}
class Div extends Calculator
{
  public function get_result($number1,$number2)
  {
   return $number1/$number2;
  }
}
class Factory
{
  public function Building($notes)
  {
   if($notes=="+")
   {
    $add=new Add();
    return $add;
   }
   elseif ($notes=="-")
   {
    $sub=new Sub();
    return $sub;
   }
   elseif($notes=="*")
   {
    $mul=new Mul();
    return $mul;
   }
   else
   {
    $div=new Div();
    return $div;
   }
  }
}