from fractions import Fraction
from collections import defaultdict
from decimal import Decimal
N=int(input())
factor=set()
factor.add(1)
factor.add(N)
for i in range(2,int(N**0.5)+3):
  if N%i==0:
    factor.add(i)
    factor.add(N//i)

factor=sorted(list(factor))

def calc_gcd(N):
  f=set()
  for i in range(1,int(N**0.5)+3):
    if N%i==0:
      f.add(i)
      f.add(N//i)
  f=list(reversed(sorted(list(f))))
  cnt=defaultdict(int)
  ans=[]
  for j in range(len(f)):
    cnt[f[j]]=N//f[j]
    for k in range(j):
      if f[k]%f[j]==0:
        cnt[f[j]]-=cnt[f[k]]
    ans.append((f[j],cnt[f[j]]))
  return ans
  
dp=[Fraction(0,1)]*(N+1)

for i in factor:
  if i==1:
    continue
  array=calc_gcd(i)
  d=Fraction(0,1)
  for j in range(len(array)):
    p,cnt=array[j]
    if p==i:
      continue
    d=(d+Fraction(cnt,i)*dp[p])
    #print(p)
  d+=1
  d=(d*Fraction(i,i-1))
  dp[i]=d
#print(dp)
a=dp[N].numerator
b=dp[N].denominator
print(f"{Decimal(a)/Decimal(b):.15f}")