H, W = map(int,input().split())
S = [list(input()) for _ in range(H)]
flag = False
for i in range(H):
  for j in range(W):
    up = down = left = right = "."
    if S[i][j] == "#":
      if i-1 >= 0:
        up = S[i-1][j]
      if j-1 >= 0:
        left = S[i][j-1]
      if i+1 <= H-1:
        down = S[i+1][j]
      if j+1 <= W-1:
        right = S[i][j+1]
      if up == down == left == right == ".":
        print("No")
        exit()
      flag = True
if flag:
  print("Yes")
else:
  print("No")