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.io.*;
  import java.math.BigInteger;
  import java.util.*;
  import static java.lang.Math.*;
  
  public class SolutionC {
      private static FastScanner in = new FastScanner();
      private static PrintWriter out =
          new PrintWriter(new BufferedOutputStream(System.out));
  
      public static void main(String[] args) {
          
          tests();
          // solve();
          
          out.close();
      }
  
      static void solve() {
          int n = in.nextInt();
          int m = in.nextInt();
          ++m;
  
          int answer = 0;
          for (int i = 30; i >= 0 && n < m; i--) {
              if ((n >> i & 1) == (m >> i & 1)) {
                  continue;
              }
              else if ((n >> i & 1) == 1 && (m >> i & 1) == 0) {
                  break;
              }
              else if ((n >> i & 1) == 0 && (m >> i & 1) == 1) {
                  answer |= 1 << i;
              }
          }
  
          out.println(answer);
          
      }
  
      static void tests() {
          int t = in.nextInt();
          while (t-- > 0) {
              solve();
          }
      }
  
      private static class FastScanner {
          private BufferedReader br;
          private StringTokenizer st;
      
          public FastScanner() {
              br = new BufferedReader(new InputStreamReader(System.in));
          }
      
          String next() {
              while (st == null || !st.hasMoreElements()) {
                  try {
                      st = new StringTokenizer(br.readLine());
                  } catch (IOException e) { e.printStackTrace(); }
              }
              return st.nextToken();
          }
      
          int nextInt() { return Integer.parseInt(next()); }
      
          long nextLong() { return Long.parseLong(next()); }
      
          double nextDouble() { return Double.parseDouble(next()); }
      
          String nextLine() {
              String str = "";
              try { str = br.readLine(); } 
              catch (IOException e) { e.printStackTrace(); }
              return str;
          }
      }
  }
  