#4方向走査
#下、右、上、左
dy=[1,0,-1,0]
dx=[0,1,0,-1]

H,W=map(int,input().split())

field=[]
for _ in range(H):
  field.append(list(input()))

is_success=True

for y in range(H):
  for x in range(W):
    if field[y][x]==".":
      continue
    
    for k in range(4):
      tmp_y=y+dy[k]
      tmp_x=x+dx[k]

      if tmp_y<0 or tmp_y>=H or tmp_x<0 or tmp_x>=W:
        continue
      if field[tmp_y][tmp_x]==".":
        break
      if k==3:
        print("No")
        exit()
print("Yes")