Given a year, report if it is a leap year.
The tricky thing here is that a leap year in the Gregorian calendar occurs:
- on every year that is evenly divisible by 4
- except every year that is evenly divisible by 100
- unless the year is also evenly divisible by 400
For example, 1997 is not a leap year, but 1996 is. 1900 is not a leap year, but 2000 is.