func main()
	var n: int :: cui@inputInt()
	var dp: []float :: #[n + 1]float
	do dp[0] :: 0.0
	
	for i(1, n)
		var p: float :: 0.0
		for j(0, i - 1)
			var x: float :: dp[j]
			var y: float :: dp[i - 1 - j]
			var pi: float :: 1.0 / i $ float * (x + y)
			do p :+ pi
		end for
		do dp[i] :: p + 1.0
	end for
	
	do cui@print("\{dp[n]}\n")
end func