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.util.*;
  public class Main {
  
      public static long helper(String s){
          long score=0;
          int count=1;
          for(int i=1;i<s.length();i++){
              if(s.charAt(i)==s.charAt(i-1)){
                  count+=1;
              }
              else{
                  score+=((long)count*count);
                  count=1;
              }
          }
  
  
          return score+=(count*count);
      }
  
  
      public static void main(String[] args) {
          FastScanner fs=new FastScanner();
          PrintWriter out=new PrintWriter(System.out);
          int t=fs.nextInt();
          while(t-->0){
              int n=fs.nextInt();
              int m= fs.nextInt()+1;
  
              int fa=0;
  
              int i=Integer.highestOneBit(m);
              i = (int)(Math.log(i) / Math.log(2));
              while(i>=0){
                  if((n^fa)>m)
                      break;
                  if((m&(1<<i))!=0){
                      if((n&(1<<i))!=0){
                          i-=1;
                          continue;
                      }
                      else{
                          fa+=(1<<i);
                          i-=1;
                          continue;
                      }
                  }
                  else{
                      i-=1;
                  }
              }
              out.println(fa);
  
  
          }
          out.close();
  
  //        int f[]=fs.readArray((1<<n));
  //
  //        int dp[][]=new int[(1<<n)][n+1];
  //
  //        for(int t=0;t<(1<<n);t++){
  //            dp[t][0]=f[t];
  //        }
  //        for(int t=0;t<(1<<n);t++){
  //            for(int i=1;i<n+1;i++){
  //                if((t&(1<<(i-1)))!=0){
  //                    dp[t][i]=dp[t][i-1]+dp[t^(1<<(i-1))][i];
  //                }
  //                else{
  //                    dp[t][i]=dp[t][i-1];
  //                }
  //            }
  //        }
  //        for(int i=0;i<(1<<n);i++){
  //            out.print(dp[i][n]+" ");
  //        }
  
          out.println();
          out.close();
  
  
  
  
         
  
  
  
  
  
  
      }
      static class FastScanner {
          BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
          StringTokenizer st=new StringTokenizer("");
          public String next() {
              while (!st.hasMoreElements())
                  try {
                      st=new StringTokenizer(br.readLine());
                  } catch (IOException e) {
                      e.printStackTrace();
                  }
              return st.nextToken();
          }
  
          int nextInt() {
              return Integer.parseInt(next());
          }
          int[] readArray(int n) {
              int[] a=new int[n];
              for (int i=0; i<n; i++) a[i]=nextInt();
              return a;
          }
          long nextLong() {
              return Long.parseLong(next());
          }
      }
  }
  