1 FON
  
 A phone number maintenance program:
  
 FON       - Give all phone numbers
 FON NAME  - Give the phone number and address of the desired person.
 FON CHA   - Make a change in this person's name, address, or phone number.
 FON IN    - Add a new name to the list.
 FON XX    - Delete a name from the list.
  
