h,w=map(int,input().split())
g=[input() for _ in range(h)]
for x in range(h):
  for y in range(w):
    if g[x][y:]=='#':
      f=1
      for dx,dy in ((1,0),(0,1),(-1,0),(0,-1)):
        nx,ny=x+dx,y+dy
        if nx<0 or nx>=h or ny<0 or ny>=w:
          continue
        elif g[nx][ny]=='#':
          f=0
      if f:
        print('No')
        break
  else:
    continue
  break
else:
  print('Yes')