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

mx = [0, 1, 0, -1]
my = [1, 0, -1, 0]
for i in range(h):
  for  j in range(w):
    if table[i][j] == "#":
      for k in range(4):
        tx, ty = j + mx[k], i + my[k]
        if 0 <= tx < w and 0 <= ty < h and table[ty][tx] == "#":
          break
      else:
        print("No")
print("Yes")
