old_contents: #!/usr/bin/env python3
  for i in range(1000):
      print(337*i%1000+1)
  
new_contents: #!/usr/bin/env python3
  
  import sys
  
  # This submission exposes a bug in an older version of the output validator
  # where the valid range of possible submissions becomes empty because the range
  # of possible values was updated incorrectly.
  # The expected verdict is WA, but with the bug present, it would give RTE.
  
  min_hidden = 1
  max_hidden = 1000
  
  for guess in [400, 700, 1, 600]:
      print(guess)
      ans = input()
      if ans == 'correct':
          break
      elif ans == 'lower':
          max_hidden = min(max_hidden, guess-1)
      elif ans == 'higher':
          min_hidden = max(min_hidden, guess-1)
      else:
          assert False
  
      assert min_hidden <= max_hidden
  
subject: Fix counterexample to be more explicit