
h, w = list(map(int, input().split()))
s = [list(input()) for i in range(h)]
dir = [[-1, 0], [1, 0], [0, -1], [0, 1]]
for y in range(h):
    for x in range(w):
        can_put = True
        if s[y][x] == "#":
            for dx, dy in dir:
                cx = x + dx
                cy = y + dy
                if cx >= 0 and cx < w and cy >= 0 and cy < h:
                    if s[cy][cx] == "#":
                        can_put = True
                        break
            else:
                can_put = False
        if can_put == False:
            break
if can_put == True:
    print("Yes")
else:
    print("No")
