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 static java.lang.Math.*;
  import java.util.*;
  import java.io.*;
  import java.math.*;
   
  public class x1554C
  {
      public static void main(String hi[]) throws Exception
      {
          BufferedReader infile = new BufferedReader(new InputStreamReader(System.in));
          StringTokenizer st = new StringTokenizer(infile.readLine());
          int T = Integer.parseInt(st.nextToken());
          StringBuilder sb = new StringBuilder();
          while(T-->0)
          {
              st = new StringTokenizer(infile.readLine());
              int N = Integer.parseInt(st.nextToken());
              int M = Integer.parseInt(st.nextToken());
              sb.append(solve(N, M)+"\n");
          }
          System.out.print(sb);
      }
      public static int solve(int N, int M)
      {
          int res = 0;
          for(int b=29; b >= 0; b--)
          {
              if(((res^N)|((1<<b)-1)) <= M)
                  res |= 1<<b;
          }
          return res;
      }
      public static int[] readArr(int N, BufferedReader infile, StringTokenizer st) throws Exception
      {
          int[] arr = new int[N];
          st = new StringTokenizer(infile.readLine());
          for(int i=0; i < N; i++)
              arr[i] = Integer.parseInt(st.nextToken());
          return arr;
      }
  }