h,w = map(int,input().split())
li = [input() for _ in range(h)]
dx = [1,0,-1,0]
dy = [0,1,0,-1]

for i in range(h):
  for j in range(w):
    if li[i][j] == ".":
      break
    for k in range(4):
      if not(0<=i+dx[k]<h) or not(0<=j+dy[k]<w):
        continue
      else:
        if li[i+dx[k]][j+dy[k]] == "#":
          break
    else:
      print("No")
      exit()
print("Yes")