Nami found two binary numbers A,B i.e., numbers containing only zero or one. Let the i th bit of A and i th bit of B differ by d. Her Logpost has broken and in order to find the next island she needs to form a binary number C such that the i th bit of C = 1 if 2^d(2 to the power of d) is even, else it should be 0.

CONSTRAINTS :

1 <= T <= 100000
Both A, B are of same length. Don't ignore leading zeros. A, B have at most 100 bits

INPUT :

First line contains the number of test cases T
For each test case, 2 lines containing A and B respectively

OUTPUT :

For each test case print the number in binary format in new line.