B"Petya and his friend, robot Petya++, like to solve exciting math problems. One day Petya++ came up with the numbers n and x and wrote the following equality on the board: n & (n+1) & ... & m = x, where & denotes the bitwise AND operation. Then he suggested his friend Petya find such a minimal m ( m ge n ) that the equality on the board holds. Unfortunately, Petya couldn't solve this problem in his head and decided to ask for computer help. He quickly wrote a program and found the answer. Can you solve this difficult problem? Each test contains multiple test cases. The first line contains the number of test cases t ( 1 <= t <= 2000 ). The description of the test cases follows. The only line of each test case contains two integers n , x ( 0 <= n, x <= 10^{18} ). For every test case, output the smallest possible value of m such that equality holds. If the equality does not hold for any m , print -1 instead. We can show that if the required m exists, it does not exceed 5 cdot 10^{18} . In the first example, 10 & 11 = 10 , but 10 & 11 & 12 = 8 , so the answer is 12 . In the second example, 10 = 10 , so the answer is 10 . In the third example, we can see that the required m does not exist, so we have to print -1 . "...