text: import sys
  from typing import List, Optional, Tuple
  
  from icontract import ensure
  
  
  @ensure(
      lambda result, total: result is None or result[0] + result[1] == total,
      "Returned items sum to the right total",
  )
  @ensure(
      lambda result, items: result is None or all(r in items for r in result),
      "Returned values appear in the input",
  )
  @ensure(
      lambda result, items: result is None
      or result[0] != result[1]
      or items.count(result[0]) > 1,
      "A duplicated result was produced from different input items",
  )
  def find_pair_with_sum(items: List[int], total: int) -> Optional[Tuple[int, int]]:
      """Find the two entries that sum to ``total``."""
      for i, x in enumerate(items):
          for y in items[i + 1 :]:
              if x + y == total:
                  return (x, y)
      return None
  
  
  if __name__ == "__main__":
      entries = list(map(int, sys.stdin.read().split()))
      print(find_pair_with_sum(entries, 2020))
  