(* O(h w) *)
let h, w = Scanf.scanf " %d %d" @@ fun a b -> a, b
let sss = Array.init h @@ fun _ -> Scanf.scanf " %s" @@ fun s -> s
let _ =
  for i = 0 to h - 1 do
    for j = 0 to w - 1 do
      if sss.(i).[j] = '#' then
        let f (dy, dx) =
          let y, x = i + dy, j + dx in
          0 <= y && y < h && 0 <= x && x < w && sss.(y).[x] = '#' in
        if not @@ List.exists f [-1, 0; 0, -1; 1, 0; 0, 1] then (print_endline "No"; exit 0)
    done
  done;
  print_endline "Yes"