description: Alice gave Bob two integers a and b (a > 0 and b ≥ 0). Being a curious boy, Bob wrote down an array of non-negative integers with \operatorname{MEX} value of all elements equal to a and \operatorname{XOR} value of all elements equal to b.
  
  What is the shortest possible length of the array Bob wrote?
  
  Recall that the \operatorname{MEX} (Minimum EXcluded) of an array is the minimum non-negative integer that does not belong to the array and the \operatorname{XOR} of an array is the [bitwise XOR](https://en.wikipedia.org/wiki/Bitwise_operation#XOR) of all the elements of the array.
  
  Input
  
  The input consists of multiple test cases. The first line contains an integer t (1 ≤ t ≤ 5 ⋅ 10^4) — the number of test cases. The description of the test cases follows.
  
  The only line of each test case contains two integers a and b (1 ≤ a ≤ 3 ⋅ 10^5; 0 ≤ b ≤ 3 ⋅ 10^5) — the \operatorname{MEX} and \operatorname{XOR} of the array, respectively.
  
  Output
  
  For each test case, output one (positive) integer — the length of the shortest array with \operatorname{MEX} a and \operatorname{XOR} b. We can show that such an array always exists.
  
  Example
  
  Input
  
  
  5
  1 1
  2 1
  2 0
  1 10000
  2 10000
  
  
  Output
  
  
  3
  2
  3
  2
  3
  
  Note
  
  In the first test case, one of the shortest arrays with \operatorname{MEX} 1 and \operatorname{XOR} 1 is [0, 2020, 2021].
  
  In the second test case, one of the shortest arrays with \operatorname{MEX} 2 and \operatorname{XOR} 1 is [0, 1].
  
  It can be shown that these arrays are the shortest arrays possible.
solution: import java.util.Scanner;
  
  public class B {
      static int[] xorMex = new int[(int) 3e5 + 1];
  
      public static void main(String[] args) {
          Scanner scn = new Scanner(System.in);
          StringBuilder sb = new StringBuilder();
          int xor = 0;
          for (int i = 0; i < xorMex.length; i++) {
              xor ^= i;
              xorMex[i] = xor;
          }
  
  
          int test = scn.nextInt();
          while (test-- > 0) {
              int a = scn.nextInt();
              int b = scn.nextInt();
  
              int ans = a + 1;
              if (xorMex[a - 1] == b) {
                  ans = a;
              }
              if (xorMex[a] == b) {
                  ans = a + 2;
              }
              sb.append(ans);
              sb.append("\n");
  
          }
          System.out.println(sb);
      }
  }
  