h, w = map(int, input().split())
grid = [list(input()) for _ in range(h)]

check = [(-1, 0), (0, -1), (1, 0), (0, 1)]
for j in range(h):
  for i in range(w):
    if grid[i][j] == "#":
      temp = [(i+cx, j+cy) for cx, cy in check if (0<= i+cx <w and 0<= j+cy <h)]
      count = 0
      for t_cx, t_cy in temp:
        if grid[t_cx][t_cy] == "#":
          count += 1
      if count == 0:
        print("No")
        exit()
print("Yes")