h, w = map(int, input().split())
s = ["."+input()+"." for i in range(h)]
s = ["."*w] + s + ["."*w]

for i in range(1,h+1):
  for j in range(1,w+1):
    if s[i][j] == "#":
      if s[i][j+1] == s[i][j-1] == s[i+1][j] == s[i-1][j] == ".":
        print("No")
        exit()

print("Yes")