use strict;
use warnings;

my $min = 1000000;
my $max = 0;
while (<DATA>) {
    m/(\d+)\D+(\d+)/;
    $min = $1 if $1 < $min;
    $max = $2 if $2 > $max;
}
print "$min-$max";

__DATA__
6-7
1 - 5
3 to 24
6 thru 9
2 through 11