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

for i in range(h):
    for j in range(w):
        if pic[i][j] == "#":
            # 上下左右の順に判定
            # １つでもあれば次へ
            if ((i-1 > 0 and pic[i-1][j] == "#")
                or 
                (i+1 < h and pic[i+1][j] == "#")
                or
                (j-1 > 0 and pic[i][j-1] == "#")
                or
                (j+1 < w and pic[i][j+1] == "#") ):
                continue
            else:
                print("No")
                exit()

print("Yes")
