program atcoder
   implicit none
   integer A, B, C, D, X, Y
   read *, A, B, C, D
   
   X=int(A+D-1/D)
   Y=int(C+B-1/B)
    if (X > Y) then
     print *,'No'
    else
     print *,'Yes'
    end if
end program atcoder