use strict;
use warnings;

my @group1 = ('A','B','C','D');
my @group2 = ('E','F','G','H');
my $string="DEABCDGHEF";
my $group = join '', @group1[0..2], @group2[2,3];
print "Match: $1\n" while $string =~ /([$group]{5})/g;