description: You are given two integers n and m. Find the \operatorname{MEX} of the sequence n ⊕ 0, n ⊕ 1, …, n ⊕ m. Here, ⊕ 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. 
  
  Input
  
  The first line contains a single integer t (1 ≤ t ≤ 30 000) — the number of test cases.
  
  The first and only line of each test case contains two integers n and m (0 ≤ n, m ≤ 10^9).
  
  Output
  
  For each test case, print a single integer — the answer to the problem.
  
  Example
  
  Input
  
  
  5
  3 5
  4 6
  3 2
  69 696
  123456 654321
  
  
  Output
  
  
  4
  3
  0
  640
  530866
  
  Note
  
  In the first test case, the sequence is 3 ⊕ 0, 3 ⊕ 1, 3 ⊕ 2, 3 ⊕ 3, 3 ⊕ 4, 3 ⊕ 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 ⊕ 0, 4 ⊕ 1, 4 ⊕ 2, 4 ⊕ 3, 4 ⊕ 4, 4 ⊕ 5, 4 ⊕ 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 ⊕ 0, 3 ⊕ 1, 3 ⊕ 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.
solution: import java.util.*;
  
  public class Practice {
      public static void main(String[] args) {
          Scanner sc = new Scanner(System.in);
          int t = sc.nextInt();
          while (t-->0) {
              String a = (Integer.toBinaryString(sc.nextInt()));
              String b = (Integer.toBinaryString(sc.nextInt() + 1));
              int[] val1 = new int[32];
              int[] val2 = new int[32];
              int index = 31;
              for (int i = a.length() - 1; i >= 0; i--) {
                  val1[index] = a.charAt(i) - '0';
                  index--;
              }
              index = 31;
              for (int i = b.length() - 1; i >= 0; i--) {
                  val2[index] = b.charAt(i) - '0';
                  index--;
              }
              StringBuilder ans = new StringBuilder();
              for (int i = 0; i < 32; i++) {
                  if (val1[i] == val2[i]) ans.append(0);
                  else if (val1[i] == 1 && val2[i] == 0) {
                      while (i < 32) {
                          ans.append(0);
                          i++;
                      }
                  } else {
                      ans.append(1);
                  }
              }
              System.out.println(Integer.parseInt(ans.toString(), 2));
          }
      }
  }
  
  