import sys
#import collections as col
input=sys.stdin.readline
enum=enumerate
inf=1001001001
eps=1e-7
upb=1e+4
lmax=300

mod = 10**9+7
NN = 2 * 10**5
g1 = [1, 1] # factorial
g2 = [1, 1] # factorial^(-1)
inverse = [0, 1] # tmp

def linput(ty=int, cvt=list):
	return cvt(map(ty,input().split()))

def vinput(rep=1, ty=int, cvt=list):
	return cvt(ty(input().rstrip()) for _ in "*"*rep)

def modinv(x, mod=mod):
	return pow(x, mod-2, mod)

def ratioal(x, y, mod=mod):
	### = x/y (mod m)
	re = x * modinv(y)
	return re % mod

def facto(x, y, mod):
	### y*(y+1)*...*(x-1)*x
	### = x!/(y-1)!
	
	re = 1
	for i in range(y, x+1):
		re *= i
		re %= mod
	#print(re, file=sys.stderr)
	return re

def comb(n, r, mod=mod):
    if ( r<0 or r>n ):
        return 0
    #r = min(r, n-r)
    #return facto(n, n-r+1, mod) * g2[r] % mod
    return g1[n] * g2[r] * g2[n-r] % mod

def init_fac():
	for i in range( 2, NN + 1 ):
		g1.append( ( g1[-1] * i ) % mod )
		inverse.append( ( -inverse[mod % i] * (mod//i) ) % mod )
		g2.append( (g2[-1] * inverse[-1]) % mod )

init_fac()

def zeta(s):
	out = 0.
	pp = float(inf)
	
	for m in range(1,lmax+1):
		ins = 0.
		for j in range(1,m+1):
			c1 = (-1)**(j-1)
			c2 = comb(m-1, j-1)
			c3 = j**(-s)
			ins += c1*c2*c3
		ins *= 2**(-m) / (1 - 2**(1-s))
		out += ins
	
		if abs(pp - ins) < eps:
			break
		if abs(out) > upb:
			break
		
		pp = ins
	
	return out


def main():
	N, = linput()

	res = zeta(N)
	print(res)


if __name__=="__main__":
	main()