#Grid Repainting 2

#初期化
S = []
p = []
flag = True

#入力
H,W = map(int, input().split())
for i in range(H):
	s = input()
	s_list = list(s)
	S.append(s_list)

#計算
for i in range(0, W-1, 1):
	for j in range(0, H-1, 1):
		if S[i][j] == "#" and S[i+1][j] == "." and S[i][j+1] == "."  and S[i-1][j] == "." and S[i][j-1] == "." :
			flag = False
		

#出力
if flag == True:
	print("Yes")

else:
	print("No")