@A = ("Red", "Green", "Yellow");
@B = ("Yellow", "Black","Yellow","Red", "White", "Yellow");

##</code><code>##

> Red at index 3
> Green is missing
> Yellow at index 0, 2 and 5
> Elements from B were detected 4 times in A

##</code><code>##

foreach $x (@A){
    foreach $y (@B){
    if ($y eq $x){
    print "$y\n";
	}
	elsif ($x ne$y){
    print "$x";
	}
  }
}