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 C_Mikasa{
      public static void main(String[] args) {
          FastScanner s= new FastScanner();
          StringBuilder res = new StringBuilder();
          int t=s.nextInt();
          int p=0;
          while(p<t){
          int n=s.nextInt();
          int m=s.nextInt();
          if(n>m){
              res.append("0\n");
              p++;
              continue;
          }
          int first[]= new int[32];
          int second[]= new int[32];
          int num1=n;
          int k=0;
          while(num1>0){
              int yo=num1&1;
              first[k]=yo;
              num1=num1>>1;
              k++;
  
          }
          k=0;
           num1=m;
           while(num1>0){
              int yo=num1&1;
              second[k]=yo;
              num1=num1>>1;
              k++;
  
          }
          // for(int i=0;i<32;i++){
          //     System.out.print(first[i]+" ");
          // }
          // System.out.println();
  
          // for(int i=0;i<32;i++){
          //     System.out.print(second[i]+" ");
          // }
          // System.out.println();
          long min=Long.MAX_VALUE;
          long val=0;
          for(int i=31;i>=0;i--){
              if(second[i]==0){
                  int num2=1^first[i];
                  long pow=0;
                  
                    pow=((long)Math.pow(2,i))*num2;
                    min=Math.min(min,(val+pow));
                   
                  
                 
                 
              }
              else{
                  long numm=((long)Math.pow(2,i))*(1^first[i]);
                  val+=numm;
              }
          }
          res.append(min+"\n");
          p++;
      }
      System.out.println(res);
  
  
      }
      static class FastScanner {
  		BufferedReader br;
  		StringTokenizer st;
   
  		public FastScanner(String s) {
  			try {
  				br = new BufferedReader(new FileReader(s));
  			} catch (FileNotFoundException e) {
  				// TODO Auto-generated catch block
  				e.printStackTrace();
  			}
  		}
   
  		public FastScanner() {
  			br = new BufferedReader(new InputStreamReader(System.in));
  		}
   
  		String nextToken() {
  			while (st == null || !st.hasMoreElements()) {
  				try {
  					st = new StringTokenizer(br.readLine());
  				} catch (IOException e) {
  					// TODO Auto-generated catch block
  					e.printStackTrace();
  				}
  			}
  			return st.nextToken();
  		}
   
  		int nextInt() {
  			return Integer.parseInt(nextToken());
  		}
   
  		long nextLong() {
  			return Long.parseLong(nextToken());
  		}
   
  		double nextDouble() {
  			return Double.parseDouble(nextToken());
  		}
  	}
  
  
  
  
  }