use strict;
use warnings;

my @array1 = <DATA>;
chomp @array1;

sub outlinish_transform {
        return join("\n", map { $_->[0] } sort { _outlinish_st() } map { [ $_, [split /\./,$_] ] } @array1);
}

sub straight_outlinish {
        return join("\n", sort { _outlinish() } @array1);
}

sub _outlinish {

   my @one = split /\./, $a;
   my @two = split /\./, $b;

   my $max = @one > @two ? @one : @two;

   for my $i (0 .. $max-1) {
       if (my $res = ($one[$i] || 0) <=> ($two[$i] || 0)) {
           return $res;
       }
   }
}

sub _outlinish_st {

   my $max = @$a > @$b ? @$a : @$b;

   for my $i (0 .. $max-1) {
       if (my $res = ($a->[1][$i] || 0) <=> ($b->[1][$i] || 0)) {
           return $res;
       }
   }
}

__DATA__
1
1.1
1.2
1.3
1.3.1
1.3.2
1.3.2.1
1.2.1
1.2.2.1
1.4