CF1554C Mikasa

You are given two integers $ n $ and $ m $ . Find the $ \operatorname{MEX} $ of the sequence $ n \oplus 0, n \oplus 1, \ldots, n \oplus m $ . Here, $ \oplus $ is the [bitwise XOR operator](https://en.wikipedia.org/wiki/Bitwise_operation#XOR). $ \operatorname{MEX} $ of the sequence of non-negative integers is the smallest non-negative integer that doesn't appear in this sequence. For example, $ \operatorname{MEX}(0, 1, 2, 4) = 3 $ , and $ \operatorname{MEX}(1, 2021) = 0 $ .

The first line contains a single integer $ t $ ( $ 1 \le t \le 30\,000 $ ) — the number of test cases. The first and only line of each test case contains two integers $ n $ and $ m $ ( $ 0 \le n, m \le 10^9 $ ).

For each test case, print a single integer — the answer to the problem.

In the first test case, the sequence is $ 3 \oplus 0, 3 \oplus 1, 3 \oplus 2, 3 \oplus 3, 3 \oplus 4, 3 \oplus 5 $ , or $ 3, 2, 1, 0, 7, 6 $ . The smallest non-negative integer which isn't present in the sequence i. e. the $ \operatorname{MEX} $ of the sequence is $ 4 $ . In the second test case, the sequence is $ 4 \oplus 0, 4 \oplus 1, 4 \oplus 2, 4 \oplus 3, 4 \oplus 4, 4 \oplus 5, 4 \oplus 6 $ , or $ 4, 5, 6, 7, 0, 1, 2 $ . The smallest non-negative integer which isn't present in the sequence i. e. the $ \operatorname{MEX} $ of the sequence is $ 3 $ . In the third test case, the sequence is $ 3 \oplus 0, 3 \oplus 1, 3 \oplus 2 $ , or $ 3, 2, 1 $ . The smallest non-negative integer which isn't present in the sequence i. e. the $ \operatorname{MEX} $ of the sequence is $ 0 $ .