Function S($o)
Dim $i, $, $k, $t, $x,$v

For $x = 0 to 16
	Redim $r[3], $c[3], $q[3], $s[3, 3, $x]
	
	For $ = 0 to 7
		For $i = 0 to 3
			$v = $o[$ mod 4,$i]
			if $<4
				$k = 3-2*($<2)-($i<2)
				$r[$i] = $r[$i] + $v
				$c[$] = $c[$] + $v
				$q[$k] = $q[$k] + $v

				$s[$, $i, $x] = $v
			else
				if 0=instr(join($r),x)
					exit
				else
				$k=@
				for $t = 1 to 4
					if 0=instr($c[$-4]+$r[$i]+$q[3-2*($<6)-($i<2)],$t) + $v
						$k=$k+$t
					endif
				next

				if 1=($k^)
					$o[$-4,$i]=$k
					$=7 $i=3
EndFunction