# -*- coding: utf-8 -*-
h,w = map(int, input().split())
board = {}
board[-1] = ["-"] * h
board[h] = ["-"] * h
for hi in range(h):
  board[hi] = {}
  board[hi][-1] = ["-"] * w
  board[hi][w] = ["-"] * w
  row = list(input())
  for wi in range(w):
    board[hi][wi] = row[wi]

res="Yes"
for hi in range(h):
  if res == "No":
    break
  for wi in range(w):
    if board[hi][wi] == "#" and board[hi-1][wi] != "#" and board[hi][wi-1] != "#" and board[hi+1][wi] != "#" and board[hi][wi+1] != "#":
        res = "No"
        break

print(res)
