program problemB
  implicit none


integer(8) :: n,m, yr, l, i, k, j,judge, small, kref, r, t, f, ref
integer(8) :: BNUM, RNUM, NMAX, count,MMAX, sum, A, B, C, D,multi,countA,countC
character(len=4) :: color



read(*,*) A,B,C,D


countA=0
countC=0
do while (A>0)
  A=A-D
  countA=countA+1
end do
do while (C>0)
  C=C-B
  countC=countC+1
end do

if (countA>=countC) then
  write(*,*) 'Yes'
else
  write(*,*) 'No'
end if 

stop
end program
