H,W = map(int, input().split())
s = [list(input()) for i in range(H)]

for h in range(H):
    for w in range(W):
        try:
            if s[h][w] == '#':
                if s[h - 1][w] != '#' and s[h + 1][w] != '#' and s[h][w - 1] != '#' and s[h][w + 1] != '#':
                    print('No')
                    exit()
        except:
            continue
print('Yes')
