The happy time of the young wizards did not last two days, and the three deans were discharged.

On this day, when Snape finished Potions class and left the Potions classroom in a blink of an eye, Arthur slowly walked out of the classroom amid a group of sympathetic eyes.

"Professor Snape!"

Arthur walked into the office of the head of the Slytherin Academy, closed the door slightly, and stared at Professor Snape, who was standing in front of the locker, moving busily.

"It's some potion material. You're going to help me get that potions level back up within a week."

Snape took thirteen potions from the locker and placed them on his desk, without raising his head, and said coldly.

"You can make potions in the potions room next door, but that's my potions room. Remember not to tamper with anything without my permission."

After turning to close the locker, Snape looked up at Arthur. His face was gloomy, and his eyes were like those of a viper.

It's not that his attitude towards Arthur makes him look like he can't be approached.

Instead, he promised Headmaster Dumbledore that he would make the Potions level. But Snape was so busy that he turned around and forgot.

When he was discharged from the hospital yesterday, Dumbledore asked him how the Potions level was going, and he remembered that he had forgotten about it.

So after today's Potions class, I asked Arthur to come to the dean's office to find him.

As the only Potions professor at Hogwarts School of Witchcraft and Wizardry. Snape's entire year of students attend Potions class.

He simply didn't have time to make the Mono level. Thinking that Arthur could write all the levels that protect the Philosopher's Stone in Harry Potter and the Philosopher's Stone with precision.

He decided to let the genius writer play his part.

"Yes, Professor Snape."

His own dean let himself make potions, albeit with some reluctance. But he is his immediate boss, a Potions professor for the next six and a half years.

Arthur could only agree to come down.

Snape's Potions level is one of the most difficult of all the levels that protect the Philosopher's Stone.

But this level mainly tests reasoning ability, and the potions used are not the kind of advanced potions.

One puzzle, seven bottles. Among the seven bottles, there are three poisons, two nettle wine, one potion that is immune to purple flames (to go back to the previous level), and one to be immune to black flames (to the next level).

"Danger is in sight, safety is in the rear, and two of us can help you."

"Drink them down, one will lead you forward, and the other will send you back to where you came."

"Two of them are filled with nettle wine, and three killers are waiting in line."

"Choose, unless you want to stay here forever."

"We'll give you four clues to help you choose: First, no matter how cunning the poison is, they're actually on the left side of the nettle."

"Second, the solutions in the bottles on the left and right are different, and they won't work for you if you want to move forward;"

"Third, you'll find bottles of varying sizes, and there's no Grim Reaper hidden in giants and gnomes;"

"Fourth, the second on the left and the second on the right, although they look different, they taste the same."

Arthur recalls his own puzzle content in Harry Potter and the Philosopher's Stone.

It felt like his puzzle was still too simple for Muggles.

If you use the ABCD to represent each other: the potion that leads to the next level (immunity to black fire), the potion that returns to the previous level (immunity to purple fire), poison and nettle wine.

Then the meaning of the first hint is that there will always be nettle D to the right of poison C. Because there were three bottles of poison, two bottles of potions.

Then the order of poison C and nettle wine D is, CCCDD, CCDCD, CDCCD, these three order of arrangement.

From the second hint, we conclude that the first and seventh positions cannot be, leading to

Potion A for the next level. It can only be B, C, D.

Combined with a hint, it is further concluded that the first position cannot be D nettle wine, but can only be C poison or potion B that is immune to purple fire.

That is, the order of immunity to Purple Flame Potion B, Poison C and Nettle Wine D is: C (position 1) CCDDB (position seven), C (1) CDCDDB (7), C (1) DCCDB (7), B (1) CCCDD (7), B (1) CCDCD (7), B (1) CDCCD (7).

Let's not look at the third one, because this one is not based on simple alphabet reasoning, but needs to be reasoned according to the different sizes of potion bottles placed in reality.

And the hint in the fourth one, the taste is the same, and it is the same as the potion in the bottle. This hint alone lets us know that potions in position two and six can only be Poison CC or Nettle DD.

In reference to the order of the order we deduced from the first and second prompts.

We can eliminate a lot of distractions and arrive at the order of Immunity Purple Fire B, Poison C, and Nettle Wine D as:

C（1）D（2）CCD（6）B（7）、B（1）C（2）CDC（6）D（7）。

Obviously, the position of Potion (Purple Fire Immunity) A that enters the next level has now been narrowed down to positions 3, 4, and 5.

Also, I was given potions from position 3 to position 5 in the order in which they could be ordered: ACC, CAC, CCA, ACD, CAD, CDA.

These six sorting methods seem to be more numerous, but in fact, it is still to choose Potion A in positions 3, 4, and 5.

(If you're a Muggle, you must have a clear idea by now.) But if you still don't have an idea, I'm sorry, you must be a wizard who didn't get an admission letter. ）

Now, if you want to be precise about where Potion A is, it depends on the actual situation and where different potion sizes are placed.

But! We can still deduce some information based on the third prompt.

The third tip is that giants and gnomes don't have a Grim Reaper, which means that the biggest and smallest vials are not Poison C.

Assuming that Immunity Purple Fire B, Poison C, and Nettle Wine D are in the order C(1)D(2)CCD(6)B(7), then the largest and smallest bottles cannot appear in the number one position.

Then, according to the principle of non-repetition and non-invalidity of the prompt, that is, the prompt of the third article must make the conclusion of the first, second and fourth prompts further narrowed, so that the reasoner can eliminate the last distractor and successfully obtain Potion A.

This means that the largest and smallest bottles cannot appear in positions 2, 3 and 7 at the same time.

And we already know that Potion A is in positions 3, 4, and 5, and the other two bottles are Poison C.

Since the largest and smallest vials cannot contain poison, it is enough to find the largest or smallest vial in slots 3, 4, and 5, i.e. the bottle is the potion A that contains "Enter the next level" immunity to black flames.

What if the order of Immunity Purple Fire B, Poison C and Nettle Wine D is: B(1)C(2)CDC(6)D(7)?