Solve the programming task below in a Python markdown code block.
Chef has two binary strings A and B, each of length N.

Chef can rearrange both the strings in any way. Find the maximum [bitwise XOR] he can achieve if he rearranges the strings optimally.

------ Input Format ------ 

- The first line of input will contain a single integer T, denoting the number of test cases.
- Each test case consists of two lines:
- The first line of each test case contains binary string A.
- The second line of each test case contains binary string B.

------ Output Format ------ 

For each test case, output the maximum bitwise XOR of the strings in binary representation.

------ Constraints ------ 

$1 ≤ T ≤ 1000$
$1 ≤ N ≤ 5 \cdot 10^{5}$
- Strings $A$ and $B$ consist only of $0$ and $1$.
- The sum of $N$ over all test cases do not exceed $5 \cdot 10^{5}$.

----- Sample Input 1 ------ 
4
0011
1011
100
100
11111
11101
1
0

----- Sample Output 1 ------ 
1110
110
10000
1

----- explanation 1 ------ 
Test case $1$: Rearranging string $A$ as $0011$ and string $B$ as $1101$, the XOR of the strings is $0011\oplus 1101 = 1110$. It can be shown that this is the maximum XOR that can be achieved by rearranging the strings.

Test case $2$: Rearranging string $A$ as $010$ and string $B$ as $100$, the XOR of the strings is $010\oplus 100 = 110$. It can be shown that this is the maximum XOR that can be achieved by rearranging the strings.

Test case $3$: Rearranging string $A$ as $11111$ and string $B$ as $01111$, the XOR of the strings is $11111\oplus 01111 = 10000$. It can be shown that this is the maximum XOR that can be achieved by rearranging the strings.

Test case $4$: Rearranging string $A$ as $1$ and string $B$ as $0$, the XOR of the strings is $1\oplus 0 = 1$. It can be shown that this is the maximum XOR that can be achieved by rearranging the strings.