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.*;
  import java.text.*;
  import java.math.*;
  import java.util.regex.*;
  
  public class JaiShreeRam{
  	static Scanner in=new Scanner();
  	static long mod = 1000000007;
  	static char c[];
  	static ArrayList<ArrayList<Integer>> adj;
  	static int nf;
  	public static void main(String[] args) throws Exception{
  		int z=in.readInt();
  		while(z-->0) {
  			int n=in.readInt();
  			int m=in.readInt();
  			int ans=0;
  			m++;
  			for(int i=31;i>=0;i--) {
  				if(((1<<i)&m)==0&&((1<<i)&n)>=1) {
  					break;
  				}
  				else if(((1<<i)&m)>=1&&((1<<i)&n)==0) {
  					ans+=(1<<i);
  				}
  			}
  			System.out.println(ans);
  		}		
  	}
  	static int[] nextIntArray(int n){
  		int[] arr= new int[n];
  		int i=0;
  		while(i<n){
  			arr[i++]=in.readInt();
  		}
  		return arr;
  	}
  	static int[] nextIntArray1(int n){
  		int[] arr= new int[n+1];
  		int i=1;
  		while(i<=n){
  			arr[i++]=in.readInt();
  		}
  		return arr;
  	}
  	static long gcd(long a, long b) {
  		if (b==0) return a;
  		return gcd(b, a%b);
  	}
  	static class Scanner{
  		BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
  		StringTokenizer st=new StringTokenizer("");
  		String readString() {
  			while (!st.hasMoreTokens())
  				try {
  					st=new StringTokenizer(br.readLine());
  				} catch (IOException e) {
  					e.printStackTrace();
  				}
  			return st.nextToken();
  		}
  		double readDouble() {
  			return Double.parseDouble(readString());
  		}
  		int readInt() {
  			return Integer.parseInt(readString());
  		}
  		long readLong() {
  			return Long.parseLong(readString());
  		}
  	}	
  }