from functools import lru_cache
import sys, time, random
from collections import deque, Counter, defaultdict
input = lambda: sys.stdin.readline().rstrip()
ii = lambda: int(input())
mi = lambda: map(int, input().split())
li = lambda: list(mi())
inf = 2 ** 61 - 1
mod = 998244353
from math import gcd
n = ii()
ni = 1 / n

@lru_cache(None)
def solve(x):
    if x == 1:
        return 0
    ans = 1
    for i in range(2, x):
        ans += solve(gcd(x, i)) / x
    return ans * x / (x - 1)

if n >= 1000000:
    raise Exception("n is too large")
else:   
    print(solve(n))