CF893B.Beautiful Divisors

Recently Luba learned about a special kind of numbers that she calls beautiful numbers. The number is called beautiful iff its binary representation consists of k + 1 consecutive ones, and then k consecutive zeroes.

Some examples of beautiful numbers:

• 12 (110);
• 1102 (610);
• 11110002 (12010);
• 1111100002 (49610).

More formally, the number is beautiful iff there exists some positive integer k such that the number is equal to (2_k_ - 1) * (2_k_ - 1).

Luba has got an integer number n, and she wants to find its greatest beautiful divisor. Help her to find it!

最近，Luba 学习了一类特殊的数，她称之为“优美数”（beautiful numbers）。一个数被称为优美数，当且仅当它的二进制表示由 k + 1 个连续的 1 后接 k 个连续的 0 构成。

一些优美数的例子：

• $12_{10} = 1100_2$；
• $110_2 = 6_{10}$；
• $1111000_2 = 120_{10}$；
• $111110000_2 = 496_{10}$。

更严格地，一个数是优美数，当且仅当存在某个正整数 $k$，使得该数等于 $(2^{k+1} - 1) \cdot 2^k$。

Luba 得到了一个整数 $n$，她希望找出 $n$ 的最大的优美因子（即能整除 $n$ 的最大优美数）。请帮她找到它！

The only line of input contains one number n (1 ≤ n ≤ 105) — the number Luba has got.

输入仅包含一行，其中有一个数字 $n$（$1 \le n \le 10^5$）——即 Luba 得到的数字。

Output one number — the greatest beautiful divisor of Luba's number. It is obvious that the answer always exists.

输出一个数字——卢巴数字的最大优美因数。显然，答案一定存在。