use strict;
use warnings;
use Data::Dumper;

...

my %hash;
while (<INPUT>) {
   chomp;
   my @line = split /\s+/, $_;
   my ($key1,$key2) = (shift @line, shift @line);
   $hash{$key1} = $hash{$key2} = [@line];
}

print Dumper \%hash;