program b
    use,intrinsic :: iso_fortran_env
    implicit none
    integer(int32):: i
    character(2*10**5):: t


    read*, t

    do i=1,len_trim(t)
        if (t(i:i) == '?') t(i:i) = 'D'
    end do

    print'(a)', trim(t)
    
end program b