What is a benefit of peer-to-peer networking?

one person has control over who is added to the network.
backing up your work is not required.
network is extremely secure.
users are independent.

Write a program that asks the user to enter the name of an input file. if the file does not exist, the program should prompt the user to enter the file name again. if the user types quit in any uppercase/lowercase combinations, then the program should exit without any further output.