import sys
input = sys.stdin.readline

from collections import Counter
from math import gcd

N=int(input())

LIST=[]

for i in range(1,round(N**(1/2))+2):
    if N%i==0:
        LIST.append(i)
        LIST.append(N//i)

LIST=sorted(set(LIST))

from functools import lru_cache
@lru_cache(maxsize=None)
def calc(x):
    if x==1:
        return 0
    KO=Counter()

    for i in LIST[::-1]:
        if i>x:
            break
        k=x//i

        KO[i]+=k
        for j in LIST:
            if i%j==0 and j<i:
                KO[j]-=KO[i]

    score=0
    #print(KO)

    for i in LIST:
        if x==i:
            break
        score+=(calc(i))*KO[i]/(x-1)

        #print(i,score)

    #print("!",score)

    return score+x/(x-1)

print(calc(N))