my @lines = <STDIN>;
print $_ for sort cmp_ip @lines;

sub cmp_ip {
    my @c = split /\./, $a;
    my @d = split /\./, $b;

    for(0.. 3) {
        return $c[$_] <=> $d[$_] if $c[$_] != $d[$_]
    }

    return $a cmp $b
}