Don't expect the user input to contain your exit condition. Instead, accept all user input (until EOF which terminates the program) and then filter the results.

chomp( my @input = <STDIN> );

for (sort { $a <=> $b } @input) {
    next if /\D/;
    last if $_ > 1_000_000;
    print "$_\n";
}
[download]

L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)