def change(questions):
  only_int_list = []
  for i in questions:
    try:
      changed_value = int(i)
      only_int_list.append(changed_value)

    except Exception:
      pass
  return only_int_list

def main():

  numbers_list_yes = [i for i in range(10)]
  numbers_list_no = [i for i in range(10)]
  check_lists = []
  question_count = int(input())
  for _ in range(question_count):
    check_lists.append(input().split())
  for check_list in check_lists:
    if "NO" in check_list:
      only_int_list = change(check_list)
      for list_value in only_int_list:
        try:
          numbers_list_no.remove(list_value)
        except ValueError:
          continue
    else:
      only_int_list = change(check_list)
      numbers_list_yes = [x for x in only_int_list if x in numbers_list_yes]

  ans = list(set(numbers_list_yes) & set(numbers_list_no))
  print(ans[0])


if __name__ == '__main__':
  main()