#!/usr/bin/perl -w
use strict;

$"='ox'x5,
$_="1 2 3\n4 5 6\n7 8 9 "
{$^=chop$"
print"$_$^ =>"
{<>=~/^(\d)$/i&&s/$1/$^/m or redo}
(m/^($^.){3}|($^.{5}){2}$^|$^.{7}$^.{7}$^|^.(...$^){3}/smx|$.>8)
or redo}y/0-9/-/;
print