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

# #で上下左右隣接するマスに#がなければNo
s = []
for h in range(H):
    s.append(input())

for h in range(H):
    print("h: %d" % h)
    for w in range(W):
        if s[h][w] == '.':
            continue

        above = s[h - 1][w] if h >= 1 else '.'
        if above == '#':
            continue

        below = s[h + 1][w] if h < len(s) - 1 else '.'
        if below == '#':
            continue

        left = s[h][w - 1] if w >= 1 else '.'
        if left == '#':
            continue

        right = s[h][w + 1] if w < len(s[h]) - 1 else '.'
        if right == '#':
            continue

        print('No')
        exit(0)

print('Yes')