content: import java.io.*;
  import java.math.*;
  import java.security.*;
  import java.text.*;
  import java.util.*;
  import java.util.concurrent.*;
  import java.util.regex.*;
  
  public class Solution {
  
      // The sansaXor method
      static int sansaXor(int[] arr) {
          //If array length is even simply return zero
          if(arr.length % 2 == 0)
              return 0;
          //If array length is not even xor all the elements at odd positions
          int ans = 0;
          for(int i = 0; i < arr.length; i ++) {
              // As the array is zero indexed so we would check for index to be even
              // which would mean they are at odd places
              if(i % 2 == 0) {
                  ans ^= arr[i];                    
              }
          }
          return ans;
      }
  
      /* Driver Code */
      private static final Scanner scanner = new Scanner(System.in);
      public static void main(String[] args) throws IOException {
          BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(System.getenv("OUTPUT_PATH")));
          int t = scanner.nextInt();
          scanner.skip("(\r\n|[\n\r\u2028\u2029\u0085])?");
          for (int tItr = 0; tItr < t; tItr++) {
              int n = scanner.nextInt();
              scanner.skip("(\r\n|[\n\r\u2028\u2029\u0085])?");
              int[] arr = new int[n];
              String[] arrItems = scanner.nextLine().split(" ");
              scanner.skip("(\r\n|[\n\r\u2028\u2029\u0085])?");
              for (int i = 0; i < n; i++) {
                  int arrItem = Integer.parseInt(arrItems[i]);
                  arr[i] = arrItem;
              }
              int result = sansaXor(arr);
              bufferedWriter.write(String.valueOf(result));
              bufferedWriter.newLine();
          }
          bufferedWriter.close();
          scanner.close();
      }
  }
  