Usage: agecalc implements scanner for taking input of a string in the following format to represent a date. YYYY/MM/DD
$ javac AgeCalc.java
$ java AgeCalc
$ # wating for input in the form of YYYY/MM/DD
$ # will print either "You're INT years old." where INT starts at 0 or "You don't exist yet and you might be a time traveler."