DB<163> map { ($a,$b)=split /\s+/; $hash{$a}{$b}=1 } <I>;
 => (1, 1, 1, 1)

  DB<164> \%hash
 => { Canberra => { 12 => 1, 18 => 1 }, Sydney => { 12 => 1, 14 => 1 } }