from itertools import product

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

s = []
for i in range(H):
    s.append(list(input()))

res = 'Yes'
for h, w in product(range(H), range(W)):
    if s[h][w] == '#':
        if h != 0 and s[h - 1][w] == '#':
            continue
        if h != H - 1 and s[h + 1][w] == '#':
            continue
        if w != 0 and s[h][w - 1] == '#':
            continue
        if w < W - 1 and s[h][w + 1] == '#':
            continue
        else:
            res = 'No'
            exit()

print(res)
