def main():
    h, w = map(int, input().split())

    m = []
    wall = ['.' for _ in range(w + 2)]
    m.append(wall)
    for _ in range(w):
        r = ["."] + list(input()) + ["."]
        m.append(r)
    m.append(wall)

    for i in range(1, h + 1):
        for j in range(1, w + 1):
            if m[i][j] == '#':
                f = any([m[i + x][j + y] == "#" for (x, y) in ((1, 0), (-1, 0), (0, 1), (0, -1))])
                if not f:
                    print("No")
                    exit()
    else:
        print("Yes")


if __name__ == '__main__':
    main()
