Anagram

对于给定的两个由大写字母组成、长度相等的字符串S、T，你的每一次操作可以将S中的任意一个字符替换为任意一个大写字母 求可以使S变为T的**换位串**的出最小步数，并输出变换后的S，如果有多组解，输出字典序最小的那一个 **换位串**的定义如下，对于两个长度相等的字符串A、B，如果A中的字母经重新组合排列可以变为B，就称A为B的**换位串**

String $ x $ is an anagram of string $ y $ , if we can rearrange the letters in string $ x $ and get exact string $ y $ . For example, strings "DOG" and "GOD" are anagrams, so are strings "BABA" and "AABB", but strings "ABBAC" and "CAABA" are not. You are given two strings $ s $ and $ t $ of the same length, consisting of uppercase English letters. You need to get the anagram of string $ t $ from string $ s $ . You are permitted to perform the replacing operation: every operation is replacing some character from the string $ s $ by any other character. Get the anagram of string $ t $ in the least number of replacing operations. If you can get multiple anagrams of string $ t $ in the least number of operations, get the lexicographically minimal one. The lexicographic order of strings is the familiar to us "dictionary" order. Formally, the string $ p $ of length $ n $ is lexicographically smaller than string $ q $ of the same length, if $ p_{1}=q_{1} $ , $ p_{2}=q_{2} $ , ..., $ p_{k-1}=q_{k-1} $ , $ p_{k}&lt;q_{k} $ for some $ k $ ( $ 1<=k<=n $ ). Here characters in the strings are numbered from 1. The characters of the strings are compared in the alphabetic order.

The input consists of two lines. The first line contains string $ s $ , the second line contains string $ t $ . The strings have the same length (from $ 1 $ to $ 10^{5} $ characters) and consist of uppercase English letters.

In the first line print $ z $ — the minimum number of replacement operations, needed to get an anagram of string $ t $ from string $ s $ . In the second line print the lexicographically minimum anagram that could be obtained in $ z $ operations.

ABA
CBA

1
ABC

CDBABC
ADCABD

2
ADBADC

The second sample has eight anagrams of string $ t $ , that can be obtained from string $ s $ by replacing exactly two letters: "ADBADC", "ADDABC", "CDAABD", "CDBAAD", "CDBADA", "CDDABA", "DDAABC", "DDBAAC". These anagrams are listed in the lexicographical order. The lexicographically minimum anagram is "ADBADC".