入力した数字が3の倍数か3の付く数字の時に｢Nabeatsu｣と返すだけのプログラム。

nabeatsu.rb

a = ARGV[0].to_i

if a % 3 == 0
	print "Nabeatsu"
else
	while a >= 10
		c = a
		b = 0
		while c >= 10
			c /= 10
			b += 1
		end
		if c == 3
			print "Nabeatsu"
			exit
		end
		a = a - c * 10 ** b
	end
	if a == 3
		print "Nabeatsu"
	else
		print "Not Nabeatsu"
	end
end