if __name__ == '__main__':
    h, w = map(int, input().split())
    field = [list(input()) for i in range(h)]
    d = [(1, 0), (0, 1), (-1, 0), (0, -1)]
    for y in range(h):
        flag = 0
        for x in range(w):
            if field[y][x] == "#":
                for dx, dy in d:
                    if 0 <= x + dx < w and 0 <= y + dy < h:
                        if field[y + dy][x + dx] == "#":
                            flag += 1
                if flag == 0:
                    print("x = {}, y = {}".format(x, y))
                    print("No")
                    exit(0)
    print("Yes")
