This program prompts you for the current date
and several birthdates.
It computes the age in years of the youngest
person and wishes Happy Birthday as appropriate.
Minimum allowed age? 10
Current year? 2010
Current month? 2
Current day? 28
Number of people? 2

Birth year? 1970
Birth month? 2
Birth day of month? 28
Happy 40th birthday!

Birth year? 1999
Birth month? 12
Birth day of month? 31

The youngest person is age 10
Everyone is old enough.  Welcome!