Explain me this please

#1

CB number once detected should not be sub-string or super-string of any other CB number.
Ex- In 4991, both 499 and 991 are CB numbers but you can choose either 499 or 991, not both.

#2

Hey Gaurav, this means that if we can form many CB numbers from a string then if we choose a CB number that number should not be a sub-string or super-string of a CB number that you have chosen earlier.

#3

but how 499 is substring or superstring of 991

#4

499 and 991 both are the substrings of 4991. This should not be considered.

#5

One digit can be considered in only one CB Number.