from collections import defaultdict

def make_divisors(n):
    divisors = []
    i = 1
    while i ** 2 <= n:
        if n % i == 0:
            divisors.append(i)
            if i ** 2 != n:
                divisors.append(n // i)
        i += 1
    divisors.sort()
    return divisors

N = int(input())
D = make_divisors(N)
ND = len(D)
dic = defaultdict(int)

for i, d in enumerate(D[1:], start=1):
    dic2 = defaultdict(int)
    D2 = make_divisors(d)
    S = set()
    for d2 in reversed(D2):
        tmp = d // d2
        for d3 in reversed(D2):
            if d2 == d3:
                break
            if d3 % d2 == 0:
                tmp -= dic2[d3]
        dic2[d2] = tmp

    dic2[1] = d - sum(dic2.values())
    tmp = 0
    for d2 in D2[1:-1]:
        tmp += dic[d2] * dic2[d2] / d
    dic[d] = (tmp + 1) * d / (d - 1)

print(dic[N])