open Batteries

let () =
  let h, w = Scanf.scanf "%d %d " (fun a b -> a, b) in
  let arr = Array.init h (fun _ -> Scanf.scanf "%s " (fun s -> 
      let str_list = Str.split (Str.regexp "") s in
      Array.of_list str_list
    )) in

  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")
