Minimum string
Phineas and Ferb really want to get into the credits, which are stored on Candace's computer. They know that Candace is afraid to forget the password, and therefore keeps a hint to it: two strings a and b from lowercase English letters.
This morning, Ferb heard what rule from the hint can get the password itself.
Consider this operation:
Let's choose any position in the string a. Let's choose any position in the string b.
Let's swap the characters at these positions.
The password is the lexicographically smallest possible value of the string a that can result from applying an arbitrary number of operations.
Help the kids figure out the password.
Input
The first line contains the string a, the second line contains the string b (1 ≤ |a|, |b| ≤ 10^5). Both strings consist of lowercase English letters.
Output
Print the password.