Function A($)

	
	dim $i, $x, $b, $l
	$l = len($)

		redim $b[$l-1]
		for $i = 0 to $l-1
			$b[$i] = substr($,$i+1,1)
		next

		for $i = $l-2 to 0 step -2
			$x = 2*$b[$i]
			$b[$i] = iif($x>9,0+left($x,1) + right($x,1),$x)
		next

		$i = execute("$X="+join($b,'+'))

	$a = ($>3 & $<7 & $l=16-($<4) & $x mod 10=)*left($,1)