program hi
  use, intrinsic :: iso_fortran_env
  implicit none
  integer(int32) :: n
  integer(int32), allocatable :: arr(:), cnts(:)
  integer(int32) :: i
  read(input_unit, *) n
  allocate(arr(n))
  read(input_unit, *) arr(:)
  allocate(cnts(n), source = 0)
  do i = 1, n
    cnts(arr(i)) = cnts(arr(i)) + 1
  end do
  block
    integer(int32) :: ans
    ans = 0
    do i = 1, n
      ans = ans + cnts(i) / 2
    end do
    write(output_unit, '(i0)') ans
  end block
end program