The file /home/218/database.txt contains 10,000 lines of data. Each line describes
one person: Social security number, birth date (YYYYMMDD), first name, last name,
and zip code.

Here are six unexciting lines from the middle of the file:

    525373469 19630128 Nancy Frankenstein 88539
    525388530 19630228 Darcy Epstein 56906
    525397776 19710519 Frances Cadwallader 88625
    525535897 19361217 Edwin Frogmorton 07004
    525753047 19380123 Alexander Jones 24267
    525780779 19420616 Tom Wilson 39264

You are to write a program that reads this file and stores its information in a 
linked list.

Once your program has constructed the list, it should enter an interactive loop,
taking commands from the user:

FIND firstname lastname
   - display all information about the named person,
     your program must not crash if no such person exists!

ZIP zipcode
   - display the names of all people living in the given zip code

ALL lastname
   - display all information about all people who have the given last name.

OLDEST
   - print the name and zipcode of the oldest person in the database.

EXIT
   - exit from the program.