H, W = map(int, input().split())
m = [input() for _ in range(H)]
# print('m', m)
for i in range(H):
    for j in range(W):
        if m[i][j] == '#':
            # print('i j', i, j)
            for x, y in [(-1, 0), (1, 0), (0, -1), (0, 1)]:
                n_x = i + x
                n_y = j + y
                if n_x < 0 or W <= n_x:
                    continue
                if n_y < 0 or H <= n_y:
                    continue
                # print('pass')
                if m[n_x][n_y] == '#':
                    break
            else:
                print('No')
                exit()
print('Yes')
