text: #!/bin/python3
  # https://www.hackerrank.com/challenges/one-week-preparation-kit-merge-two-sorted-linked-lists/ #
  
  import math
  import os
  import random
  import re
  import sys
  
  class SinglyLinkedListNode:
      def __init__(self, node_data):
          self.data = node_data
          self.next = None
  
  class SinglyLinkedList:
      def __init__(self):
          self.head = None
          self.tail = None
  
      def insert_node(self, node_data):
          node = SinglyLinkedListNode(node_data)
  
          if not self.head:
              self.head = node
          else:
              self.tail.next = node
  
  
          self.tail = node
  
  def print_singly_linked_list(node, sep, fptr):
      while node:
          fptr.write(str(node.data))
  
          node = node.next
  
          if node:
              fptr.write(sep)
  
  # Complete the mergeLists function below.
  
  #
  # For your reference:
  #
  # SinglyLinkedListNode:
  #     int data
  #     SinglyLinkedListNode next
  #
  #
  def mergeLists(head1, head2):
      if not head1 and not head2: return head1
      elif not head1: return head2
      elif not head2: return head1
  
      result = SinglyLinkedListNode(node_data=None)
      current = result
      
      while head1 and head2:
          if head1.data <= head2.data:
              current.next = head1
              head1 = head1.next
          else:
              current.next = head2
              head2 = head2.next
          current = current.next
      
      if head1: current.next = head1
      if head2: current.next = head2
      return result.next
  
  if __name__ == '__main__':
      fptr = open(os.environ['OUTPUT_PATH'], 'w')
  
      tests = int(input())
  
      for tests_itr in range(tests):
          llist1_count = int(input())
  
          llist1 = SinglyLinkedList()
  
          for _ in range(llist1_count):
              llist1_item = int(input())
              llist1.insert_node(llist1_item)
              
          llist2_count = int(input())
  
          llist2 = SinglyLinkedList()
  
          for _ in range(llist2_count):
              llist2_item = int(input())
              llist2.insert_node(llist2_item)
  
          llist3 = mergeLists(llist1.head, llist2.head)
  
          print_singly_linked_list(llist3, ' ', fptr)
          fptr.write('\n')
  
      fptr.close()
  