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