N=int(input())
if N==1:
  print(1.2020569031595942853997381615114499907649862923404988817922715553)
elif N==2:
  print(1.0823232337111381915160036965411679027747509519187269076829762154)
elif N==3:
  print(1.036927755)
else:
  ANS=0
  for a in range(1,101):
    for b in range(a+1,100001):
      ANS+=(pow(1/a,N)-pow(1/b,N))/(b*(b-a))
  print(ANS)