H, W = map(int, input().split())
sw = [list(str(input())) for i in range(H)]
dx = [1,0,-1,0]
dy = [0,1,0,-1]

for i in range(H):
  for j in range(W):
    if sw[i][j] == "#":
      counter = 0
      for k in range(4):
        if i+dx[k] < 0 or i+dx[k] >= H or j+dy[k] < 0 or j+dy[k] >= H:
          counter += 1
        elif sw[i+dx[k]][j+dy[k]] == ".":
          counter += 1
      if counter == 4:
        print("No")
        exit()
print("Yes")