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

def check(h,w):
  ans = False
  if 0 < h:
    ans |= S[h-1][w] == "#"
  if 0 < w:
    ans |= S[h][w-1] == "#"
  if h < H-1:
    ans |= S[h+1][w] == "#"
  if w < W-1:
    ans |= S[h][w+1] == "#"
  return ans
for h in range(H):
  for w in range(W):
    if not check(h,w):
      print("No")
      exit()
print("Yes")
    