text: from tool.runners.python import SubmissionPy
  
  
  class YouyounSubmission(SubmissionPy):
      def run(self, s):
          """
          :param s: input in string format
          :return: solution flag
          """
          # Your code goes here
          n_days = 256
          fish = [0 for _ in range(10)]
          for e in map(int, s.split(',')):
              fish[int(e) + 1] += 1
          for _ in range(n_days):
              fish[:-1] = fish[1:]
              fish[-1] = fish[0]
              fish[7] += fish[0]
              fish[0] = 0
          return sum(fish)
  
  
  def test_youyoun():
      """
      Run `python -m pytest ./day-06/part-1/youyoun.py` to test the submission.
      """
      assert (
              YouyounSubmission().run(
                  """
      """.strip()
              )
              == None
      )
  