program postdocs
  implicit none
  character(200000) :: t
  integer :: n, i
  read(*,*) t
  n = len_trim(t)
  do i = 1, n
    if (t(i:i) == '?') t(i:i) = 'D'
  end do
  write(*,'(a)') trim(t)
end program postdocs