h, w = map(int, input().split())
s = [input().strip() for _ in range(h)]
for i in range(h):
    for j in range(w):
        flg = False
        if s[i][j] == '#':
            if 0 < i and s[i - 1] == '#':
                flg = True
            if i < (h - 1) and s[i][j] == '#':
                flg = True
            if 0 < j and s[i][j - 1] == '#':
                flg = True
            if j < (w - 1) and s[i][j] == '#':
                flg = True
            if not flg:
                print('No')
                exit()
print('Yes')
