from itertools import product

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

s = []
for i in range(H):
    s.append(list(input()))

for h, w in [(h, w) for h, w in product(range(H), range(W)) if s[h][w] != '.']:
    R = False
    if h > 0 and s[h - 1][w] == '#':
        # 上
        R = True
    if h < H - 2 and s[h + 1][w] == '#':
        # 下
        R = True
    if w > 0 and s[h][w - 1] == '#':
        # 左
        R = True
    if w < W - 2 and s[h][w + 1] == '#':
        # 右
        R = True

    if not R:
        print('No')
        exit()

print('Yes')