program back_and_forth
  implicit none
  integer :: x(2), y(2), dx, dy
  read(*,*) x(1), y(1), x(2), y(2)
  dx = x(2) - x(1)
  dy = y(2) - y(1)
  call out(dx, 'R')
  call out(dy, 'U')
  call out(dx, 'L')
  call out(dy + 1, 'D')
  call out(dx + 1, 'R')
  call out(dy + 1, 'U')
  call out(1, 'L')
  call out(1, 'U')
  call out(dx + 1, 'L')
  call out(dy + 1, 'D')
  call out(1, 'R')
  write(*,*)
contains
  subroutine out(n, c)
    integer, intent(in) :: n
    character(1) :: c
    integer :: i
    do i = 1, n
      write(*,'(a)',advance='no') c
    end do
  end
end program back_and_forth