# c07ex11.py
#     Leap year determination

def isLeap(year):
    if year % 4 != 0:
        return False
    elif year % 100 == 0:
        if year % 400 == 0:
            return True
        else:
            return False
    else:
        return True

def main():
    print "This program calculates whether a year is a leap year.\n"
    year = input("Enter a year: ")
    if isLeap(year):
        print year, "is a leap year."
    else:
        print year, "is not a leap year."
        
if __name__ == '__main__':
    main()