#! perl -slw
use strict;
use Time::HiRes qw[ time ];

my @a; $#a = 1e6;
my $n = 0;
$a[ $n++ ] = $_ while <>;

printf "%d records; check memory", scalar @a; <STDIN>;

my $start = time;

my @sorted = @a[
    map { unpack 'N', substr($_,-4) }
    sort
    map { pack 'NNN', $a[ $_ ] =~ m[(\d+) (\d+)], $_ }
    0..$#a
];

printf "Took %.6f seconds; check memory? ", time()- $start; <STDIN>;