inH, inW = map(int, input().split())
inMap = list()

for i in range(inH):
  inMap.append(list(input()))

def chkPaint(x,y):
  mv = [[-1,0], [1,0], [0,-1], [0,1]]
  for pos in mv:
    if x+pos[0]<0 or x+pos[0]>=inH or y+pos[1]<0 or y+pos[1]>=inH  :
      continue
    if inMap[x+pos[0]][y+pos[1]] == "#":
        return True
  return False

flg=True
for i in range(inH):
  for j in range(inW):
    if inMap[i][j] == "#":
      flg = chkPaint(i,j)
    if flg == False:
      break
  if flg == False:
    break

if flg:
  print("Yes")
else:
  print("No")
    