#! /usr/bin/perl

use autodie;
use Getopt::Std;

(my $PROG = $0) =~ s!^.*/!!;
sub usage (;\*) {
  my ($f) = @_;
  $f //= \*STDOUT;
  print STDOUT "usage: $PROG [-r LO-HI] FILE ...\n";
}

my ($lo_bound, $hi_bound) = (undef, undef);
my $bogus = 0;
my %opt; $bogus = 1 unless getopts("r:", \%opt);
if (defined $opt{"r"}) {
  if ($opt{"r"} =~ /^(\d+)?-(\d+)?$/) { ($lo_bound, $hi_bound) = ($1, $2); }
  else { $bogus = 1; }
}
if ($bogus) { usage STDERR; exit 2; }
$lo_bound //= 0;

my @bad;

LINE: while (<>) {
  chomp; s/\s*\#.*$//; next LINE if /^$/;
  die "bad line" unless /^\s*(\d+)\s*(\d+)\s*$/;
  my ($lo, $hi) = ($1, $2);
  push @bad, [$lo, $hi];
}

@bad = sort { $a->[0] <=> $b->[0] } @bad;
my ($lo, $hi) = (undef, undef);
sub emit ($$) {
  my ($lo, $hi) = @_;
  if ($hi <= $lo_bound) { return; }
  if (defined $hi_bound && $lo >= $hi_bound) { return; }
  if ($lo < $lo_bound) { $lo = $lo_bound; }
  if (defined $hi_bound && $hi > $hi_bound) { $hi = $hi_bound; }
  printf "%d %d\n", $lo - $lo_bound, $hi - $lo_bound;
}
for my $item (@bad) {
  my ($a, $b) = @$item;
  if (!defined $lo) { ($lo, $hi) = ($a, $b); }
  elsif ($a > $hi) { emit $lo, $hi; ($lo, $hi) = ($a, $b); }
  elsif ($b < $lo) { die "buggy piece of shit"; }
  else { $hi = $b; }
}
emit $lo, $hi if defined $lo;