! 2019.9.28 
!
      program answer
      implicit none
      integer :: N_i
      integer :: M_i
      double precision :: N_d
      double precision :: M_d
      double precision :: ans_d
      intrinsic dble
!
      read(*,*) N_i
      N_d = dble(N_i)
! M_i : the number of odd 
      M_i = (N_i + 1) / 2
      M_d = dble(M_i)
! 
      ans_d = M_d / N_d
      write(*,*) ans_d
      end program answer
