wOFFSETS = [(-1,0),(0,-1),(0,1),(1,0)]

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

Ses = []
for _ in range(H):
    Ses.append(input())

for y in range(H):
    for x in range(W):
        if Ses[y][x] == "#":
            found = False
            for dx, dy in OFFSETS:
                now_x = x+dx
                now_y = y+dy
                if now_x < 0 or now_x >= W:
                    continue
                if now_y < 0 or now_y >= H:
                    continue
                if Ses[now_y][now_x] == "#":
                    found = True
                    break
            if not found:
                print("No")
                exit()

print("Yes")
