use strict;
use warnings;

my @odometer = qw(0 0);
for (1..$ARGV[0]) {
    print "was: @odometer\t";
    @odometer = increment_odometer(@odometer);
    @odometer ? (print join ' ', @odometer) : (print "No more Wheels to turn! $!" and exit) ;
    print "\n";

}

sub increment_odometer {
          my @odometer = @_;
          my $wheel = $#odometer; # start at rightmost wheel

    until ($odometer[$wheel] < 9 || $wheel < 0)
    {
                          $odometer[$wheel] = 0;
                          $wheel--; # next wheel to the left
    }
    if ($wheel < 0) {
                    return; # fell off the left end; no more sequences
    } else {
                    $odometer[$wheel]++; # this wheel now turns one notch
                    return @odometer;
    }
}