CF915C.Permute Digits

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 $a$ .