You have a list of contacts where each contact has a list of emails.
We want to do a deduplication over these contacts (some kind of merge) such that all contacts that are completely included in another contact should be removed. If a contact is only partially included in another contact then we should keep it.

Example 1:
C1 - a@test.com, a@gmail.com
C2- a@test.com
Should return only C1 because C2 is fully included in C1

Example 2:
C1 - a@test.com, b@gmail.com
C2 - a@test.com, b@hotmail.com
Even though a@test.com is found in both C1 and C2 we still need to return C1 and C2 as both contacts have an email that is not included in the other.