$3.$ Trace the following code:

$```$

public class finalq$3\{$

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

int n$=3$;

what$($n$,\text{'}$A$\text{'},\text{'}$B$\text{'},\text{'}$C$\text{'})$;

$\}$

private static void what$($int j$,$ char a$,$ char b$,$ char c$)\{$

System.out.println$($j $+""+$ a $+""+$ b $+""+$ c$)$;

if $($j $==1)$

$\{$ return;$\}$

what $($j$-1,$ a$,$ c$,$ b$)$;

what $($j$-1,$ c$,$ a$,$ b$)$;

$\}$

$\}$

$```$