h, w = map(int, input().split())
masu = [[0 for y in range(h)] for x in range(w)]
for y in range(0, h):
    z = list(input())
    for x in range(0, w):
        masu[y][x] = z[x]
hantei = "Yes"
for y in range(0, h):
    for x in range(0, w):
        if (masu[y][x] == "#"):
            if (not((y > 0 and masu[y - 1][x] == "#") or (y < h - 1 and masu[y + 1][x] == "#") or (x > 0 and masu[y][x - 1] == "#") or (x < w - 1 and masu[y][x + 1] == "#"))):
                hantei = "No"
print (hantei)