def main():
    H, W = map(int, input().split())
    S = ['.'*W]+['.'+input()+'.' for _ in range(H)]+['.'*W]

    for h in range(1, H+1):
        for w in range(1, W+1):
            if S[h][w] == '#':
                if S[h-1][w] == '.' and S[h+1][w] == '.' and S[h][w+1] == '.' and S[h][w-1] == '.':
                    return False
    return True


print('Yes' if main() else 'No')
