w, h = map(int, input().split())
field = [list(input()) for _ in range(h)]

for y in range(h):
    for x in range(w):
        if field[y][x] == "#":
            try:
                if("#" in [field[y + 1][x], field[y - 1][x], field[y][x + 1], field[y][x - 1]]):
                    pass
                else:
                    print("No")
                    quit()
            except IndexError:
                False

print("Yes")