oracle SQL return invalid data and way to find which data

Hi  I have issue with SQL and when convert data to numeric  return error.  Then how to identify or skip invalid data to run the sql

SELECT *

FROM (

    SELECT to_number(trim(ariline_no)) , to_number(COUNT(CREW_no)) NONO

    FROM MAIN

    GROUP BY to_number(trim(ariline_no))

    ) C

error says

ORA-01722: invalid number

01722. 00000 -  "invalid number"

*Cause:    The specified number was invalid.

*Action:   Specify a valid number.

+++++++++++++++++++++

If I  alter this way  its works .

SELECT *

FROM (

    SELECT ariline_no, count(CREW_no) NONO

    FROM MAIN

    GROUP BY ariline_no

    ) C

++++++++++++++++++++++

but I need to find which data is cause of this issue