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 Main {
  	public static void main(String[] args) throws Exception {
  
  		
  		
  		
  		int t=sc.nextInt();
  		while(t-->0) {
  			long n=sc.nextInt();
  			long m=sc.nextInt();
  			if(m<n) {
  				pw.println(0);
  			}else {
  				long low=0;
  				long high=Integer.MAX_VALUE/2;
  				long mid=low+high>>1;
  				while(low<=high) {
  					long temp=mid;
  					long pos=1;
  					long v=n;
  					while(temp>0) {
  						while((n&pos)!=0) {
  							pos<<=1;
  						}
  						if((temp&1)!=0) {
  							v|=pos;
  						}
  						temp>>=1;
  						pos<<=1;
  					}
  					if(v>m) {
  						high=mid-1;
  					}else {
  						low=mid+1;
  					}
  					mid=low+high>>1;
  				}
  				long temp=low;
  				long pos=1;
  				long v=n;
  				while(temp>0) {
  					while((n&pos)!=0) {
  						pos<<=1;
  					}
  					if((temp&1)!=0) {
  						v+=pos;
  					}
  					temp>>=1;
  						pos<<=1;
  				}
  				pw.println(v^n);
  				
  			}
  		}
  		
  		pw.close();
  	}
  
  	static class Scanner {
  		StringTokenizer st;
  		BufferedReader br;
  
  		public Scanner(InputStream s) {
  			br = new BufferedReader(new InputStreamReader(s));
  		}
  
  		public Scanner(FileReader r) {
  			br = new BufferedReader(r);
  		}
  
  		public String next() throws IOException {
  			while (st == null || !st.hasMoreTokens())
  				st = new StringTokenizer(br.readLine());
  			return st.nextToken();
  		}
  
  		public int nextInt() throws IOException {
  			return Integer.parseInt(next());
  		}
  
  		public long nextLong() throws IOException {
  			return Long.parseLong(next());
  		}
  
  		public String nextLine() throws IOException {
  			return br.readLine();
  		}
  
  		public double nextDouble() throws IOException {
  			String x = next();
  			StringBuilder sb = new StringBuilder("0");
  			double res = 0, f = 1;
  			boolean dec = false, neg = false;
  			int start = 0;
  			if (x.charAt(0) == '-') {
  				neg = true;
  				start++;
  			}
  			for (int i = start; i < x.length(); i++)
  				if (x.charAt(i) == '.') {
  					res = Long.parseLong(sb.toString());
  					sb = new StringBuilder("0");
  					dec = true;
  				} else {
  					sb.append(x.charAt(i));
  					if (dec)
  						f *= 10;
  				}
  			res += Long.parseLong(sb.toString()) / f;
  			return res * (neg ? -1 : 1);
  		}
  
  		public long[] nextlongArray(int n) throws IOException {
  			long[] a = new long[n];
  			for (int i = 0; i < n; i++)
  				a[i] = nextLong();
  			return a;
  		}
  
  		public Long[] nextLongArray(int n) throws IOException {
  			Long[] a = new Long[n];
  			for (int i = 0; i < n; i++)
  				a[i] = nextLong();
  			return a;
  		}
  
  		public int[] nextIntArray(int n) throws IOException {
  			int[] a = new int[n];
  			for (int i = 0; i < n; i++)
  				a[i] = nextInt();
  			return a;
  		}
  
  		public Integer[] nextIntegerArray(int n) throws IOException {
  			Integer[] a = new Integer[n];
  			for (int i = 0; i < n; i++)
  				a[i] = nextInt();
  			return a;
  		}
  
  		public boolean ready() throws IOException {
  			return br.ready();
  		}
  
  	}
  
  	static class pair implements Comparable<pair> {
  		long x;
  		long y;
  
  		public pair(long x, long y) {
  			this.x = x;
  			this.y = y;
  		}
  
  		public String toString() {
  			return x + " " + y;
  		}
  
  		public boolean equals(Object o) {
  			if (o instanceof pair) {
  				pair p = (pair) o;
  				return p.x == x && p.y == y;
  			}
  			return false;
  		}
  
  		public int hashCode() {
  			return new Long(x).hashCode() * 31 + new Long(y).hashCode();
  		}
  
  		public int compareTo(pair other) {
  			if (this.x == other.x) {
  				return Long.compare(this.y, other.y);
  			}
  			return Long.compare(this.x, other.x);
  		}
  	}
  
  	static class tuble implements Comparable<tuble> {
  		int x;
  		int y;
  		int z;
  
  		public tuble(int x, int y, int z) {
  			this.x = x;
  			this.y = y;
  			this.z = z;
  		}
  
  		public String toString() {
  			return x + " " + y + " " + z;
  		}
  
  		public int compareTo(tuble other) {
  			if (this.x == other.x) {
  				if (this.y == other.y) {
  					return this.z - other.z;
  				}
  				return this.y - other.y;
  			} else {
  				return this.x - other.x;
  			}
  		}
  	}
  
  	static long mod = 1000000007;
  	static Random rn = new Random();
  	static Scanner sc = new Scanner(System.in);
  	static PrintWriter pw = new PrintWriter(System.out);
  }