program battle
  implicit none
  integer :: a, b, c, d
  read(*,*) a, b, c, d
  do
    c = c-b
    if (c <= 0) then
      write(*,'(a)') "Yes"
      stop
    end if
    a = a-d
    if (a <= 0) then
      write(*,'(a)') "No"
      stop
    end if
  end do
end program battle