$0 = 0
$3 = 0
$4 = 0
$100 = W * H
while($0 < $100)
  $7 = $0 / W
  $8 = $0 % W
  $7 = $7 + 1
  $8 = $8 + 1
  $1 = A[$7,$8]
  $2 = B[$7,$8]
  $6 = $1 - $2
  $4 = $4 + $6
  $6 = $6 * $0
  $3 = $3 + $6
  $0 = $0 + 1
end
$0 = $3 / $4
$7 = $0 / W
$8 = $0 % W
$7 = $7 + 1
$8 = $8 + 1
return($7, $8)