số 8 ở đâu trong ma trận số này?
999999999999999999999999999999999999
999999999999999999999999999999999999
999999999999999999999999999999999999
999999999999999999999999999999999999
999999999999999899999999999999999999
999999999999999999999999999999999999
999999999999999999999999999999999999
999999999999999999999999999999999999
999999999999999999999999999999999999
hàng thứ 5 tui nói không bao giờ sai
xí,quá dễ
hàng 5 chữ thứ 17