my $length = 87688;
my @ranges;
while(<>){
  chomp;
  my @range = split / /;
  push @ranges,[@range];
}

# Using Schwartzian transform, sort the ranges from the
# longest to the shortest
@ranges = map {
  [$_->[1],$_->[2]]
} sort {
  $b->[0] <=> $a->[0]
} map {
  my $remainder = $_->[1] - $_->[0];
  $remainder += $length if $remainder < 0;
  [$remainder,$_->[0],$_->[1]]
} @ranges;

# checks that a subrange is included in a wider range
sub included {
  my($o0,$o1,$i0,$i1) = @_;
  if ($o0 <= $o1){
    return ($i0 <= $i1 and $i0 >= $o0 and $i1 <= $o1)
  } else { # outer range is circular
    return ($i1 <= $o1 or $i0 >= $o0)
  }
} # included

my @ranges_kept;
while (my $range = pop @ranges) {
  push @ranges_kept,$range
    unless grep included(@$_,@$range),@ranges;
}

warn scalar @ranges_kept," ranges kept.\n";
print $_->[0],' ',$_->[1],"\n" foreach (@ranges_kept);
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