H,W=map(int,input().split())
s=[input() for _ in range(H)]

for i in range(H):
  h=i
  for j in range(W):
    w=s[h][j]
    if w=='#':
      w=s[i].find('#')
      cnt=0
      for j,k in ([1,0], [-1,0], [0,1], [0,-1]):
        new_h, new_w=h+j, w+k
        if new_h<0 or new_h>=H or new_w<0 or new_w>=W:
          continue
        elif s[new_h][new_w] == '#':
          cnt+=1
          break
      if cnt==0:
        print('No')
        exit()
print('Yes')