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.lang.*;
  import java.util.*;
  import java.io.*;
  import java.math.*;
  
  public class Main {
      static void deal(int n,int m) {
          int l = 0;
          while(n>=(1<<l)) l++;
          int d = (1<<l);
          int m1 = m %d;
          m = m>>l;
          m = m<<l;
          if(m1<n) {
              out.println(m);
              return;
          }
          int res = 0;
          while(n<=m1) {
              int n1 = n;
              int index=0;
              while(n1<=m1) {
                  n1 = n1|(1<<index);
                  index++;
              }
              if(index ==0) {
                  out.println(m+res);
                  return;
              } else {
                  index--;
                  m1 -= (1<<index);
                  res += (1<<index);
              }
          }
          out.println(m+res);
      }
  
  	public static void main(String[] args) {
          MyScanner sc = new MyScanner();
          out = new PrintWriter(new BufferedOutputStream(System.out));
          int t = sc.nextInt();
          for(int i=0;i<t;i++) {
              int n = sc.nextInt();
              int m = sc.nextInt();
              deal(n,m);
          }
          out.close();
      }
      
      //-----------PrintWriter for faster output---------------------------------
      public static PrintWriter out;
      
      //-----------MyScanner class for faster input----------
      public static class MyScanner {
          BufferedReader br;
          StringTokenizer st;
          
          public MyScanner() {
                  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;
          }
          
      }
  }