my @a = ( 42, 42, 43, 43, 43, 44, 45, 46, 41, -13 );
my @b = ( 43, 45, -13, 43 );
my @c = @a;

@b = sort @b;

for my $i ( 0 .. $#b  ) {
    next if $i > 0 && $b[ $i ] == $b[ $i - 1];
    for my $j ( 0 .. $#c ) {
        next unless defined $c[ $j ];
        $c[ $j ] = undef, last if $c[ $j ] == $b[ $i ];
    }
}
@c = grep { defined } @c;
print join ', ', @c; print "\n";