Problem A. Alphabetic replacement ≡

Statement

You are given two strings of small Latin letters, S and T. Some letters of string S may be replaced by letters of T according to the following rules:

1. Each letter from T may be used only once or not used at all.
2. Letters from T must be used in order from left to right. In other words, if letter S_i is replaced by letter T_p, letter S_j is replaced by letter T_q, and i < j, then p < q.

You program must modify string S according to the rules above to get lexicographically smallest string.

Input file format

First line of input file contains string S. Second line of input file contains string T.

Output file format

Output file must contain optimally modified string S.

Constraints

0 < |S|, |T| ≤ 10⁵

Sample tests

aaa
abacaba

aaa

ababcaba
abca

aaaacaba