Permute Digits

给出两个正整数a,b。在十进制下重排a，构造一个不超过b的最大数，不能有前导零。允许不去重排a。 输入格式： 第一行一个数a ($1\le a\le 10^{18}$)。第二行一个数b ($1\le b\le 10^{18}$) 数没有前导零，数据保证有解。 输出格式： 输出一个数，表示a重排后不超过b的最大数，不应该有前导零。 输出的数的长度应该与a相等，它应该是a的一个排列。

You are given two positive integer numbers $ a $ and $ b $ . Permute (change order) of the digits of $ a $ to construct maximal number not exceeding $ b $ . No number in input and/or output can start with the digit 0. It is allowed to leave $ a $ as it is.

The first line contains integer $ a $ ( $ 1<=a<=10^{18} $ ). The second line contains integer $ b $ ( $ 1<=b<=10^{18} $ ). Numbers don't have leading zeroes. It is guaranteed that answer exists.

Print the maximum possible number that is a permutation of digits of $ a $ and is not greater than $ b $ . The answer can't have any leading zeroes. It is guaranteed that the answer exists. The number in the output should have exactly the same length as number $ a $ . It should be a permutation of digits of $ a $ .

123
222

213

3921
10000

9321

4940
5000

4940