h, w = map(int, input().split())
s = [input() for i in range(n)]
for i in range(h):
  for j in range(w):
    if s[i][j] = "#":
      d = set()
      if i>0:
        d.add(s[i-1][j])
      if i<h-1:
        d.add(s[i+1][j])
      if j>0:
        d.add(s[i][j-1])
      if j<w-1:
        d.add(s[i][j+1])
      if "#" not in d:
        print("No")
        exit()
print("Yes")