Function s($x)
	Dim $j,$,$a[2*$x],$p,$_
	For $j = 0 to 2*$x
		$a[$j] = $j-$x
	Next

	gosub d
	For $ = 1 to $x
		For $j = 1 to $
			$p=1
			gosub d
		Next
		$=$+($x>$)
		For $j = 1 to $
			$p=-1
			gosub d
		Next
	Next
	If 0= $x MOD 2
	 $=1
	 $p=1
	 gosub n
	endif
	For $ = 1 to $x
		If $x MOD 2
		 $p=1
		 gosub n
		 $=$+($x>$)
		endif
		If $ < $x
			$p=-1
			gosub n
		endif
		If 0= $x MOD 2
		 $=$+($x>$)
		 $p=1
		 gosub n
		endif
	Next
	$s=Split($s,a)
exit
:n
	For $j = $ to $x
		gosub d
	next
return
:d
	If $s
		$_ = AScan($a,$j*$p)
		$a[AScan($a,0)]=$j*$p
		$a[$_]=0
		$s = $s + a
	EndIf
	For Each $_ in $a
		$s= $s + SubStr("W B",1+($_=)+2*($_>),1)
	next
return
EndFunction