What is the output of the following code snippet? $($if there is any kind of error indicate this in your answer with the word "error"$)$

public class Chapter$6$Problems

$\{$

public static void main$($String$[]$ args$)$

$\{$

new ChildClass$(4)$;

$\}$

$\}$

class ParentClass

$\{$

public static int a$=2$;

public ParentClass$($int i$)$

$\{$

a$+=2$;

System.out.print$($a$+$i$)$; $//$notice the ln is missing

$\}$

$\}$

class ChildClass extends ParentClass

$\{$

public ChildClass$($int i$)$

$\{$

System.out.print$($i$)$; $//$notice the ln is missing

$\}$

public ChildClass$()$

$\{$

this$(12)$;

System.out.print$(3)$; $//$notice the ln is missing

$\}$

$\}$