H, W = map(int,input().split())
List = [list("." +input()+ ".") for i in range(H)]
B = ["."]*(W+2)
List.insert(0,B)
List.append(B)

for i in range(1,W+1):
  for j in range(1,H+1):
    if List[i][j]=="#" and List[i-1][j]==List[i][j-1]\
        ==List[i][j+1]==List[i+1][j]==".":
      print("No")
      break
  else:
    continue
  break  

else:print("Yes")