var k: int
func main()
	do @k :: cui@inputInt()
	var ans: float :: e(0)
	do cui@print("\{ans.toStrFmt(".5f")}\n")
	
	func e(x: int): float
		if(x >= @k)
			ret 0.0
		end if
		var res: float :: 0.0
		for i(1, 6)
			do res :+ e(x + i) / 6.0
		end for
		do res :+ 1.0
		ret res
	end func
end func