from copy import deepcopy, copy
import sys
import io
from typing import Optional


import time
from random import randrange, randint, random, uniform
import sys, io
from collections import deque, defaultdict
import heapq
from collections import Counter
import math
from math import gcd
from functools import lru_cache

from itertools import combinations, permutations
from bisect import bisect_left, bisect_right

from itertools import groupby
from itertools import accumulate

from math import factorial

import decimal
import math

# from sortedcontainers import SortedList

# import pypyjit
# pypyjit.set_param("max_unroll_recursion=-1")

sys.setrecursionlimit(1000000000)
sys.set_int_max_str_digits(1000000000)

start_time = time.time()


N = int(input())


def divisor(n) -> list:
    sq = n**0.5
    border = int(sq)
    table = []
    bigs = []
    for small in range(1, border + 1):
        if n % small == 0:
            table.append(small)
            big = n // small
            bigs.append(big)
    if border == sq:  # nが平方数
        bigs.pop()
    table += reversed(bigs)
    return table


divs = divisor(N)
divs = sorted(divs)

dp = defaultdict(int)

for i in range(len(divs)):
    n = divs[i]
    if n == 1:
        continue

    divs_now = divisor(n)
    divs_now = list(reversed(sorted(divs_now)))

    counter = defaultdict(int)
    for j in range(len(divs_now)):
        counter[divs_now[j]] += n // divs_now[j]
        for k in range(j):
            if divs_now[k] % divs_now[j] == 0:
                counter[divs_now[j]] -= counter[divs_now[k]]

    for num in counter:
        if num == n:
            continue
        dp[n] += 1 / n * counter[num] * dp[num]
    dp[n] += 1
    dp[n] *= (n) / (n - 1)

print(dp[N])