H, W = map(int, input().split())
s = [input() for _ in range(H)]
cnt = sum([v.count('#') for v in s])

ans = 0
for h in range(H):
    for w in range(W):
        if s[h][w] == '#':
            s[h][w] == '*'
            ans += 1
        if s[h][w] == '*':
            if w < W - 1 and s[h][w + 1] == '#':
                s[h][w + 1] == '*'
                ans += 1
            if h < H - 1 and s[h + 1][w] == '#':
                s[h + 1][w] == '*'
                ans += 1
                
print('Yes' if ans == cnt else 'No')