program main
  implicit none
  integer*8::N,A,B,W,i,str,str_max,tmp,dp_min
  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
  tmp = MIN(dp(0),dp(1))

  do i=2,N
     if(tmp.eq.dp(0)) then
        str_max = 0
     end if
     tmp = tmp + D(i)
     dp_min = tmp
     str_max = MIN(str_max, (D(i)+A)/B)
     do str=str_max+1,1,-1
        dp(str) = dp(str-1) - A + B*str
        dp_min = MIN(dp_min, dp(str))
     end do
     dp(0) = tmp
     str_max = str_max + 1
     tmp = dp_min
  end do

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

end program main