Two Subsequences 2

A subsequence of a string A is a non-empty string made by choosing one or more characters from A. The chosen characters must keep their original order in A, but they do not have to be adjacent.

Given two strings A and B, find the shortest string that is a subsequence of A but is not a subsequence of B.

The first line contains string A, and the second line contains string B.

Both strings consist only of lowercase English letters, and each length is at most 2000. Every input is guaranteed to have an answer.

On the first line, print the length of the shortest string that is a subsequence of A but not a subsequence of B.

On the second line, print one such string. If multiple strings are possible, print any one of them.