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.*;
  import java.io.*;
   
  public class lab7{
  	public static void main(String[] args) throws IOException{
  		in.init(System.in);
  		PrintWriter writer=new PrintWriter(System.out);
  		int t=in.nextInt();
  		for(int a=0;a<t;a++) {
  			int n=in.nextInt(),m=in.nextInt();
  			if(n>m) {
  				System.out.println(0);
  				continue;
  			}
  			String x=Integer.toBinaryString(n);
  			String y=Integer.toBinaryString(m+1);
  			char[] C1=new char[y.length()],C2=new char[y.length()];
  			String z="";
  			boolean check=false;
  			for(int i=0;i<y.length();i++)
  				C1[i]='0';
  			for(int i=0;i<x.length();i++)
  				C1[y.length()-i-1]=x.charAt(x.length()-i-1);
  			for(int i=0;i<y.length();i++)
  				C2[i]=y.charAt(i);
  			for(int i=0;i<y.length();i++) {
  				if(check && C1[i]=='0' && C2[i]=='1') {
  					z+="0";
  				}
  				else if(C1[i]=='1' && C2[i]=='0') {
  					check=true;
  					z+="1";
  				}
  				else 
  					z+=y.charAt(i);
  			}
  			System.out.println(Integer.parseInt(x,2)^Integer.parseInt(z,2));
  		}
  		writer.flush();
  		writer.close();
  	}
  }
   
  class in {
      static BufferedReader reader;
      static StringTokenizer tokenizer;
      static void init(InputStream input) {
          reader = new BufferedReader(new InputStreamReader(input) );
          tokenizer = new StringTokenizer("");
      }
      static String next() throws IOException {
          while ( ! tokenizer.hasMoreTokens() ) 
              tokenizer = new StringTokenizer(reader.readLine() );
          return tokenizer.nextToken();
      }
      static int nextInt() throws IOException {
          return Integer.parseInt(next());
      }
      static long nextLong() throws IOException {
          return Long.parseLong(next());
      }
      static double nextDouble() throws IOException {
          return Double.parseDouble(next());
      }
  }