H, W = map(int, input().split())
grid = [input() for i in range(H)]

if H == 1 and W == 1 and grid[0][0] == "#":
    print("Yes")
    exit()

sharp_counter = 0
for h in range(H):
    for w in range(W):
        if grid[h][w] == ".":
            continue

        sharp_counter += 1
        nearby_sharp_counter = 0

        for a, b in [(-1, 0), (1, 0), (0, -1), (0, 1)]:
            if h+a < 0 or h+a >= H or w+b < 0 or w+b >= W:
                continue
            elif grid[h+a][w+b] == "#":
                nearby_sharp_counter += 1
        
        if nearby_sharp_counter == 0:
            print("No")
            exit()

if sharp_counter == 0:
    print("No")
    exit()

print("Yes")