Recently, a new social network site, Facepage, was founded. Given the current trends, the managers of Facepage are convinced that this will be the new hype in the near future.

When new users want to join Facepage, they first need to fill in a form with their personal information $($i$.$e$.,$ ID$,$ name, email, and date of birth$).$ A user has a unique ID$.$ Afterwards, an account is created. An account is uniquely identified by an account number, automatically generated by the database system. The user needs to specify which type of account he$/$she prefers: a business account or a personal account. A business