CF169B.Replacing Digits

You are given an integer $a$ that consists of $n$ digits. You are also given a sequence of digits $s$ of length $m$ . The digit in position $j$ ( $1<=j<=m$ ) of sequence $s$ means that you can choose an arbitrary position $i$ ( $1<=i<=n$ ) in $a$ and replace the digit in the chosen position $i$ with $s_{j}$ . Each element in the sequence $s$ can participate in no more than one replacing operation.

Your task is to perform such sequence of replacements, that the given number $a$ gets maximum value. You are allowed to use not all elements from $s$ .

The first line contains positive integer $a$ . Its length $n$ is positive and doesn't exceed $10^{5}$ . The second line contains sequence of digits $s$ . Its length $m$ is positive and doesn't exceed $10^{5}$ . The digits in the sequence $s$ are written consecutively without any separators.

The given number $a$ doesn't contain leading zeroes.

Print the maximum value that can be obtained from $a$ after a series of replacements. You are allowed to use not all elements from $s$ . The printed number shouldn't contain any leading zeroes.