Working: As the program is run, just enter the data for 4 customers and start the transaction. It asks for the ids of the lender and the borrower along with the amount which is to be transferred. The program could be made recurring but the purpose of OOP would be served by a single transaction as well. The data is private and can't be accessed without the class functions ensuring that there is no data breach.

The lending model implemented in this program is centralised as there is a hub/server which stores the information about the transaction and keeps a check that amount more than the balance is not being lended.

Demerits of a centralised lending system:

Third party involvement Chances of data breach There may be a delay due to traffic in the server