Increment and Decrement Operations in PHP

Consider the following code:

<?php
	$num = 0;
	$num = $num + 1; // add the number 1 to the variable $num
	echo $num;       // will output 1
?>

As you already know, this code can be rewritten in a shortened form using the += operator:

<?php
	$num = 0;
	$num += 1; // add the number 1 to the variable $num
	echo $num; // will output 1
?>

In fact, adding one is so common in programming that an even more abbreviated syntax was invented for this operation - a special operator ++ (increment), which increases the value of a variable by 1.

Let's rewrite our code using it:

<?php
	$num = 0;
	$num++;    // add the number 1 to the variable a
	echo $num; // will output 1
?>

In addition to the ++ operation, there is also the -- (decrement) operation, which decreases the value of a variable by 1. See the example:

<?php
	$num = 0;
	$num--;    // subtract the number 1 from the variable $num
	echo $num; // will output -1
?>

Modify this code so that it uses increment and decrement operations:

<?php
	$num = 10;
	$num = $num + 1;
	$num = $num + 1;
	$num = $num - 1;
	echo $num;
?>