#!/usr/bin/perl
use strict;
use warnings;
use Data::Dumper;
$Data::Dumper::Indent = 1;

my %hash;
while (my $rec = <DATA>){
  chomp $rec;
  # declare the array
  my ($key, @array) = split(/ /, $rec, 2);
  $hash{$key} = \@array;
}
print Dumper \%hash;

__DATA__
1 2 3 4
5 6 7 8