for k in range(h):
    for j in range(w):
        x,y = k,j
        if a[x][y] == "#":
            for i in range(4):
                xi,yi = x+dx[i],y+dy[i]
                if 0 <= xi < h and 0 <= yi < w and a[xi][yi] == "#":
                    break
            else:
                print("No")
                exit()
 
print("Yes")