h,w = map(int,input().split())
s = [list(input()) for _ in range(w)]

def search(i,j):
  flg = False
  if 0<=i-1:
    if s[i-1][j] == "#":
      flg = True
  if i+1 < h:
    if s[i+1][j] == "#":
      flg = True 
  if 0<=j-1:
    if s[i][j-1] == "#":
      flg = True
  if j+1 < w:
    if s[i][j+1] == "#":
      flg = True
  return flg
  
for i in range(h):
  for j in range(w):
    if s[i][j]=="#" and search(i,j)==False:
      print("No")
      break
  else:
    continue
  break
else:
  print("Yes")
    