H, W = map(int, input().split())
S = [input() for i in range(W)]
dd = ((0, -1), (-1, 0), (0, 1), (1, 0))
for i in range(H):
  for j in range(W):
    if S[i][j] == '.':
      continue
    for dx, dy in dd:
      nx = j + dx
      ny = i + dy
      if 0 <= nx < W and 0 <= ny < H:
        if S[ny][nx] == '#':
          break
    else:
      print('No')
      quit()
print('Yes')
