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.*;
  public class check1  {
  
  	public static long find(long n,long m)
  	{
  		if(n>m) return 0;
  		m++;
  		long ans = 0;
  		for(long k=35;k>=0;k--)
  		{
  			//n-m : 1-1 or 0-0		
  			if(((n>>k)&1) == ((m>>k)&1)) continue;
  			
  			//n==1 && m==0
  			if(((n>>k)&1) == 1) break;
  			
  			//m==1 && n==0
  			if(((m>>k)&1) == 1) ans = ans|(1<<k);
  		}	
  		return ans;
  	}
      public static void main(String[] args) throws IOException{
  
          Reader sc=new Reader();
          PrintWriter out = new PrintWriter(System.out);
          int t=sc.nextInt();
  
          while(t-->0)
          {		
  				long n = sc.nextLong();
  				long m = sc.nextLong();
  				System.out.println(find(n,m));
          }
          out.flush();
      }
  
      public static long power(long x,long power)
      {
          if(power==0) return 1;
  
          long ans1 = power(x,power/2);
          ans1=ans1*ans1;
  
          if(power%2==0) return ans1;
          return x*ans1;
      }
  
      //    (a*a_inverse) = 1(mod m)
  //    finding a_inverse
      public static long modInverse(long a,long m)
      {
  //        works only when m is prime
          long g=gcd(a,m);
          if(g==1) return power(a,m-2,m);
          else return -1;
      }
  
      //    (x^power)mod(m)
      public static long power(long x,long power,long m)
      {
          if(power==0) return 1;
  
          long p = power(x,power/2,m)%m;
          p = (p*p)%m;
  
          if(power%2==0) return p;
          return (x*p)%m;
      }
      public static long gcd(long small,long large)
      {
          if(small==0) return large;
          return gcd(large % small,small);
      }
  
      public static boolean isprime(long no)
      {
          if(no<=1) return false;
          if(no<=3) return true;
          if(no%2==0 || no%3==0) return false;
          // 6k+1 6k+5 can be prime
          for(long i=5;i*i<=no;i+=6)
          {
              if(no%(i)==0 || no%(i+2)==0)
                  return false;
          }
          return true;
      }
  
      //    prime no smaller than or equal to n
      public static boolean[] prime_nos_till_no(int no)
      {
          boolean prime[]=new boolean[no+1];
  //        prime[i]== true means prime
  //        prime[i]== false means not a prime
  //        initialize prime array as true
  
          Arrays.fill(prime,true);
          prime[0]=false;
          for(int i=2;i*i<=no;i++)
          {
              if(prime[i]==true)
              {
                  for(int j=i*i;j<=no;j+=i)
                  {
                      prime[j]=false;
                  }
              }
          }
          return prime;
  
      }
      public static void shufflearray(long arr[])
      {
  
  
          int n=arr.length;
          Random rand=new Random();
          for(int i=0;i<n;i++)
          {
              long temp=arr[i];
              int randomPos=i+rand.nextInt(n-i);
              arr[i]=arr[randomPos];
              arr[randomPos]=temp;
          }
      }
      //       Arrays.sort(arr, new Comparator<pair>() {
  //        //@Override
  //        public int compare(pair o1, pair o2) {
  //            long l1=o1.a-o2.a;
  //            if(l1<0L) return -1;
  //            if(l1==0) return 0;
  //            return 1;
  //        }
  //    });
      static class Reader {
          final private int BUFFER_SIZE = 1 << 16;
          private DataInputStream din;
          private byte[] buffer;
          private int bufferPointer, bytesRead;
  
          public Reader() {
              din = new DataInputStream(System.in);
              buffer = new byte[BUFFER_SIZE];
              bufferPointer = bytesRead = 0;
          }
  
          public Reader(String file_name) throws IOException {
              din = new DataInputStream(new FileInputStream(file_name));
              buffer = new byte[BUFFER_SIZE];
              bufferPointer = bytesRead = 0;
          }
  
          public String nextLine() throws IOException {
              byte[] buf = new byte[64]; // line length
              int cnt = 0, c;
              while ((c = read()) != -1) {
                  if (c == '\n')
                      break;
                  buf[cnt++] = (byte) c;
              }
              return new String(buf, 0, cnt);
          }
          public boolean isSpaceChar(int c) {
              return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
          }
  
          public String next() throws IOException{
              int c = read();
              while (isSpaceChar(c)) c = read();
              StringBuilder res = new StringBuilder();
              do {
                  res.appendCodePoint(c);
                  c = read();
              } while (!isSpaceChar(c));
              return res.toString();
          }
  
  
          public int nextInt() throws IOException {
              int ret = 0;
              byte c = read();
              while (c <= ' ')
                  c = read();
              boolean neg = (c == '-');
              if (neg)
                  c = read();
              do {
                  ret = ret * 10 + c - '0';
              } while ((c = read()) >= '0' && c <= '9');
  
              if (neg)
                  return -ret;
              return ret;
          }
  
          public long nextLong() throws IOException {
              long ret = 0;
              byte c = read();
              while (c <= ' ')
                  c = read();
              boolean neg = (c == '-');
              if (neg)
                  c = read();
              do {
                  ret = ret * 10 + c - '0';
              }
              while ((c = read()) >= '0' && c <= '9');
              if (neg)
                  return -ret;
              return ret;
          }
  
          public double nextDouble() throws IOException {
              double ret = 0, div = 1;
              byte c = read();
              while (c <= ' ')
                  c = read();
              boolean neg = (c == '-');
              if (neg)
                  c = read();
  
              do {
                  ret = ret * 10 + c - '0';
              }
              while ((c = read()) >= '0' && c <= '9');
  
              if (c == '.') {
                  while ((c = read()) >= '0' && c <= '9') {
                      ret += (c - '0') / (div *= 10);
                  }
              }
  
              if (neg)
                  return -ret;
              return ret;
          }
  
          private void fillBuffer() throws IOException {
              bytesRead = din.read(buffer, bufferPointer = 0, BUFFER_SIZE);
              if (bytesRead == -1)
                  buffer[0] = -1;
          }
  
          private byte read() throws IOException {
              if (bufferPointer == bytesRead)
                  fillBuffer();
              return buffer[bufferPointer++];
          }
  
          public void close() throws IOException {
              if (din == null)
                  return;
              din.close();
          }
  
      }
  
  }