h, w = list(map(int, input().split()))
s = [list(input()) for i in range(h)]
dir = [[-1, 0], [1, 0], [0, -1], [0, 1]]
for y in range(h):
    for x in range(w):
        if s[y][x] == "#":
            for dx, dy in dir:
                cx = x + dx
                cy = y + dy
                if x >= 0 and x < w and y >= 0 and y < h and s[cy][cx] == "#":
                    break
            else:
                break
    else:
        continue
    print("No")
    break
else:
    print("Yes")