H,W = map(int,input().split())
maps = [input().rstrip() for x in range(H)]
for i in range(H):
  for j in range(W):
    if maps[i][j] == '#':
      count = 0
      if 0 < i-1 and maps[i-1][j] == '#':
        count += 1
      if i+1 < H and maps[i+1][j] == '#':
        count += 1
      if 0 < j-1 and maps[i][j-1] == '#':
        count += 1
      if j+1 < W and maps[i][j+1] == '#':
        count += 1
      if count == 0:
        print('No')
        exit()
print('Yes')  