Find Mirror End

Background

In a world of strings and patterns, Dawei is fascinated by symmetrical structures. He often challenges himself with puzzles involving strings that exhibit mirror-like properties.

Problem Description

Given a string, look for a mirror image (backwards) string at both the beginning and end of the given string. In other words, zero or more characters at the very beginning of the given string, and at the very end of the string in reverse order (possibly overlapping). For example, the string "abXYZba" has the mirror end "ab".

Input Format

Input is given from standard input in the following format.

$S$

Output Format

Output is printed to standard output in the following format.

The mirror end string

Sample

abXYZba

"ab"

abca

"a"

aba

"aba"

Sample Explanation

For the string "abXYZba\