C. Crossed out letter
time limit per test
1 second
memory limit per test
256 megabytes
input
standard input
output
standard output

Consider string $$$s$$$. Let's call $$$s$$$ with some single character removed – $$$s_0$$$, and without some, possibly another, character – $$$s_1$$$. You are given $$$s_0$$$ and $$$s_1$$$, find any suitable string $$$s$$$ or determine, that there are none.

Input

The first line of the input data contains one string $$$s_0$$$ consisting of lowercase English letters.

The second line of the input data contains one string $$$s_1$$$ consisting of lowercase English letters.

$$$$$$ 1 \le |s_0|, |s_1| \le 3 \cdot 10^5 $$$$$$

$$$$$$ |s_0| = |s_1| $$$$$$

Output

Print a single line $$$s$$$ consisting of lowercase English letters or "IMPOSSIBLE" (in capital letters, without quotes).

Examples
Input
abacaa
aacaba
Output
abacaba
Input
bsuir
openx
Output
IMPOSSIBLE
Note

In the first test case, removing from "abacaba" second character "b" we get $$$s_0=$$$"abacaa", and removing "abacaba" first character "b", we get $$$s_1=$$$"aacaba".

In the second test case there isn't any string $$$s$$$.