Is there any edge case i'm missing out

#1

what cases am i missing

#2

Try for this Input:
8
86922395
correct output : 4

#3

kindly give me a hint on how to proceed

#4

Intuition :
Put loop on string that will give substring of every length.
create a function that will return true if the passed number is a CB number otherwise return false.
To put a check if the digit is already a part of the any other CB number, create an boolean array say, valid which store which digits till now has been a part of any other CB number.
Take a counter and increment if a CB number is found.
At the end print the count