import sys

H, W = map(int, input().split())
str = [input() for _ in range(H)]

for h in range(H):
  for w in range(W):
    if str[h][w] == "#":
      if h>0: 
        if str[h-1][w] == "#" : break;
      if h<H-1: 
        if str[h+1][w] == "#" : break;
      if w>0:
        if str[h][w-1] == "#" : break;
      if w<W-1:
        if str[h][w+1] == "#" : break;
      print("No")
      sys.exit()
print("Yes")