h, w = map(int, input().split())
s = [input() for i in range(h)]

ns = ((0, -1), (-1, 0), (0, 1), (1, 0))
for i in range(h):
    for j in range(w):
        if s[i][j] != '#':
            continue
        for dx, dy in ns:
            nx = i + dx
            ny = j + dy
            if nx < 0 or nx >= w:
                continue
            if ny < 0 or ny >= h:
                continue
            if s[nx][ny] == '#':
                break
        else:
            print('No')
            exit()

print('Yes')