use strict;
my @a = qw(fred bob joe jim ethfgh mary elaine foo bar bob foo too);
my @b = qw(frank joe jim dfkjhgdkjfg mary bob srere dfhgerg wet sdfwer mary);

my (%seenA, %seenB);
{
	my $i = 0;
	@seenA{@a}=undef;
	@seenB{@b}=undef;
	my $last = -1;
	@a = map {exists $seenB{$_} ? ($last = $_) : (defined($last) ? ($last = undef) : ())} @a;
	my $last = -1;
	@b = map {exists $seenA{$_} ? ($last = $_) : (defined($last) ? ($last = undef) : ())} @b;
}

print "@a\n";
print "@b\n\n";

shift(@a) unless defined $a[0];
shift(@b) unless defined $b[0];
pop(@a) unless defined $a[-1];
pop(@b) unless defined $b[-1];

print "@a\n";
print "@b\n\n";

my @result;

while (@a and @a > @result) {
	my $start = 0;
	while (@b - $start > @result) {
		my $end = 0;
		my @maybe = ();
		$end++ while (defined($a[$end]) and defined($b[$start+$end]) and $a[$end] eq $b[$start+$end]);
		if (--$end > @result) {
			@result = @a[0..$end];
		}
		$start++;
	}
	shift(@a);
}

print "@result\n";