$0 = H * W
$1 = 0
$2 = 0
$3 = 0
while($1 < $0)
  $4 = $1 / W
  $5 = $1 % W
  $6 = A[$4+1,$5+1] - B[$4+1,$5+1]
  $2 = $2 + $6 * $1
  $3 = $3 + $6
  $1 = $1 + 1
end
$7 = $2 / $3
$8 = $7 / W + 1
$9 = $7 % W + 1
return($8,$9)