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.BufferedReader;
  import java.io.IOException;
  import java.io.InputStreamReader;
  import java.util.PriorityQueue;
  
  public class Main{
  	static int[] convertIntToBits(int x){
  		int [] bitRep = new int[32];
  		int i=0;
  		while(x!=0){
  			bitRep[i] = x&1;
  			x = x>>1;
  			i++;
  		}
  		return bitRep;
  	}
  	static int convertBitToInt(int [] x){
  		int ret= 0;
  		for(int i=31;i>=0;i--){
  			ret = ret<<1;
  			ret |= x[i];
  		}
  		return ret;
  	}
  	public static void main (String args[]) throws NumberFormatException, IOException {
  		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
  		int numTc = Integer.parseInt(br.readLine());
  		for(int tc = 0; tc <numTc; tc++) {
  			String input1 []= br.readLine().split(" ");
  			
  			int n = Integer.parseInt(input1[0]);
  
  			int m = Integer.parseInt(input1[1]);
  
  			if(m<n)
  				System.out.println(0);
  			else{
  				int p = m+1;
  				int bitN []= convertIntToBits(n);
  				int bitP [] = convertIntToBits(p);
  				int ans[] = new int [32];
  				for(int i=31;i>=0;i--){
  					if(bitN[i]==0 && bitP[i]==1 )
  						ans[i] = 1;
  					else if(bitN[i]==1 && bitP[i]==0 ){
  						ans[i] = 0;
  						break;
  					}
  					else{
  						ans[i] = 0;
  					}
  				
  
  				}
  				System.out.println(convertBitToInt(ans));
  
  			}
  			
  		}
  		
  	}
  }