H, W = map(int, input().split())

s = [input() for _ in range(H)]

for h in range(H):
    for w in range(W):
        if s[h][w] == "#":
            if h > 0 and s[h-1][w] == "#":
                continue
            elif w < W-1 and s[h][w+1] == "#":
                continue
            elif h < H-1 and s[h-1][w] == "#":
                continue
            elif w > 0 and s[h][w-1] == "#":
                continue
            else:
                print("No")
                exit()
print("Yes")
