H, W = map(int, input().split())

s = [input() for i in range(H)]

for y in range(H):
  for x in range(W):
    if x-1 < 0 or y-1 < 0 or x+1 > W-1 or y+1 > H-1:
      continue
    if s[y][x] == '#' and s[y+1][x] != '#' and s[y-1][x] != '#' and s[y][x+1] != '#' and s[y][x-1] != '#':
      print("No")
print("Yes")
