open Batteries

let () =
  let h, w = Scanf.scanf "%d %d\n" (fun a b -> a, b) in

  let arr = Array.make h (Array.make w '-') in
  for i = 0 to h-1 do
    let str = read_line () in
    let chars_list = String.to_list str in
    arr.(i) <- (Array.of_list chars_list)
  done;

  let res = ref true in

  for i = 0 to h-1 do
    for j = 0 to w-1 do
      if arr.(i).(j) = '#' then (
        let tmp = ref false in
        if i <> 0 then (
          if arr.(i-1).(j) = '#' then tmp := true;
        );
        if i <> h-1 then (
          if arr.(i+1).(j) = '#' then tmp := true;
        );
        if j <> 0 then (
          if arr.(i).(j-1) = '#' then tmp := true;
        );
        if j <> w-1 then (
          if arr.(i).(j+1) = '#' then tmp := true;
        );
        if !tmp = false then res := false
      );
    done;
  done;

  print_endline (if !res then "Yes" else "No")
