class Human
    def initialize (name, year, month, day)
	@name = name
	@birth_day = Time.local(year, month, day)
    end

    def name
	return @name
    end

    def age
	time = Time.now
	a = time.year - @birth_day.year
	if time.mon < @birth_day.mon
	    a = a - 1
	elsif time.mon == @birth_day.mon
	    if time.day < @birth_day.day
		a = a - 1
	    end
	end
	return a
    end
end

class Student < Human
    def set_number (n)
	@number = n
    end

    def number
	return @number
    end
end

a = Student.new("Tetsuo Sakaguchi", 1965, 8, 22)
p(a.name)
p(a.age)
p(a)
a.set_number(84232)
p(a.number)
p(a)