program takahashi_is_missing
  implicit none
  integer :: x
  real(8) :: p, e
  character(64) :: s
  read(*,*) x
  read(*,*) p
  p = 0.01d0*p
  e = real((x+1)/2,8)/p
  write(s,'(f32.16)') e
  write(*,'(a)') trim(adjustl(s))
  stop
end program takahashi_is_missing