#!/usr/bin/perl -w
use warnings;
use strict;
use 5.10.0;

my @in_array = qw(A B C E F G);
my @out_array;
my $insert = 'D';

push @out_array,
        @in_array[0..2],
        $insert,
        @in_array[3..5];

say join (', ',  @in_array);

say join (', ',  @out_array);

exit;