H, W = map(int, input().split())
MAP = [list(input()) for h in range(H)]
b = False
for i in range(H):
    for j in range(W):
        sharp = False
        for x, y in [(0, 1), (1, 0), (0, -1), (-1, 0)]:
            dx, dy = i + x, j + y
            if 0 <= dx and 0 <= dy and dx < W and dy < H:
                if MAP[i][j] == '#' and MAP[dx][dy] == '#':
                    sharp = True
        if MAP[i][j] == '#' and not sharp:
            print('No')
            b = True
            break
    if b:
        break
else:
    print('Yes')