integer,allocatable::a(:)
  integer(kind=1)::num(1000000000)
  data num/1000000000*0_1/
  integer::i
  read *, N
  allocate(a(N))
  read *,a
  num = 0
  do i = 1, N
     num(a(i)) = MIN(num(a(i)) + 1_1,2)
  end do
  print '(i0)', COUNT(num.eq.1)
end program