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

ans = "Yes"

for y in range(h):
    for x in range(w):
        if sL[y][x] == ".":
            continue
        for dx, dy in dxy:
            if y-1 < 0 or y+1 > h-1 or x-1 < 0 or x+1 > w-1:
                continue
            if sL[y+1][x] == sL[y-1][x]  == sL[y][x+1] == sL[y][x-1] == ".":
                ans = "No"
                break

print(ans)