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(maxsize=None)
def solve(x):
    if x == 1:
        return 0
    ans = 0
    nx = x
    p = []
    for i in range(2, x):
        if i * i > nx:
            break
        if nx % i == 0:
            for j in range(i, x, i):
                for k in p:
                    if j % k == 0:
                        break
                else:
                    ans += solve(gcd(x, j))
            while nx % i == 0:
                nx //= i
            p.append(i)
    if nx > 1:
        for j in range(nx, x, nx):
            for k in p:
                if j % k == 0:
                    break
            else:
                ans += solve(gcd(x, j))
    ans += x
    return ans / (x - 1)

print(solve(n))