program main
  implicit none
  integer*8::N,A,B,W,i,str,str_max,tmp,uplimit
  integer*8,allocatable::D(:)
  integer*8,allocatable::dp(:)

  read *, N,A,B,W
  allocate(D(N))
  allocate(dp(0:N))
  read *, D

  if(B.eq.0) then
     print '(i0)', (W-N*A)
     return
  end if

  dp(0) = W

  dp(1) = W - A + B*1
  dp(0) = W + D(1)
  str_max = 1

  do i=2,N
     tmp = MINVAL(dp(0:str_max))
     if(tmp.eq.dp(0)) then
        !tabeta houga kanarazu yoi
        str_max = 0
     end if

     !str ha tamesugi nai
     str_max = MIN(str_max, (D(i)+A)/B)
     do str=str_max+1,1,-1
        dp(str) = dp(str-1) - A + B*str
     end do
     dp(0) = tmp + D(i)
     str_max = str_max + 1
  end do

  print '(i0)', MINVAL(dp(0:str_max))

end program