program main
  implicit none
  integer::N,A,B,W,i,j
  integer,allocatable::D(:)
  integer,allocatable::dp(:,:)

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

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

  do i=2,N
     dp(i,0) = MINVAL(dp(i-1,0:i-1)) + D(i)
     do j=1,i
        dp(i,j) = MAX(dp(i-1,j-1) - A + B*j,0)
     end do
  end do

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

end program