$1 = 0
$2 = 0


$3 = $1+1
$4 = $2+1
$10 = A[$3,$4]
$20 = B[$3,$4]
$0 = $10 - $20
while($0 == 0)
  $2 = $2 + 1
  $1 = $1 + ($2/W)
  $2 = $2 % W
    
  $3 = $1+1
  $4 = $2+1
  $10 = A[$3,$4]
  $20 = B[$3,$4]
  $0 = $10 - $20
end  

return($3,$4)