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

S = [list(input()) for _ in range(H)]

for h in range(H):
    for w in range(W):
        if S[h][w] == "#":
            try:
                up, down, left, right = S[H-1][W], S[H+1][W], S[H][W-1], S[H][w+1]
            except IndexError:
                pass
            if up == "." and down == "." and left == "." and right == ".":
                print("No")
                break
else:print("Yes")