h, w = map(int, input().split())
pic = []
pic.append(["."] * (w + 2))
for i in range(h):
  pic.append(["."] + list(input()) + ["."])
pic.append(["."] * (w + 2))

can_paint = True
for i in range(1, h+1):
  for j in range(1, w+1):
    up = pic[i-1][j]
    down = pic[i+1][j]
    left = pic[i][j-1]
    right = pic[i][j+1]
    if up == "." and down == "." and left == "." and right == ".":
      can_paint = False
      
if can_paint == True:
  print("Yes")
else:
  print("No")