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