H, W = map(int, input().split())
G = [input() for _ in range(H)]
dd = ((0, -1), (-1, 0), (0, 1), (1, 0))

for i in range(H):
    for j in range(W):
        if G[i][j] == '.':
            continue
        for dx, dy in dd:
            nx = j + dy; ny = i + dy
            if 0 <= nx < W and 0 <= ny < H:
                if G[ny][nx] == '#':
                    break
        else:
            print('No')
            exit()

print('Yes')