Implements a program that determines whether a provided credit card number is valid according to Luhn’s algorithm.
$ ./credit
Number: 378282246310005
AMEX
Program should behave per the example below.
Identifies following merchant:
- AMEX
- VISA
- MASTERCARD
$ ./credit
Number: 378282246310005
AMEX
$ ./credit
Number: 3782-822-463-10005
Number: foo
Number: 378282246310005
AMEX
$ ./credit
Number: 6176292929
INVALID