play a game with me

The line stopped, "Is it there yet?"

"It's here." Gu Ye said.

Everyone opened their eyes one after another: "This is it?"

Except for the different background outside, this corridor looks the same as the corridors on the upper floors, and there is no so-called back door.

Ye Tiandao: "Where is the back door? There is no door here!"

Gu Ye was also a little surprised, but this actually just proved his idea: there is no exit or entrance on the first floor of a building, what could be more abnormal than this?

Gu Ye said: "Don't limit your thinking to the door. The 'back door' can be a door or something else."

The clock in the hallway moved forward by three more frames, 15 minutes passed, and they still had more than half an hour.

Gu Ye carefully studied the structure of the first floor.There are windows on one side of the corridor, and rooms on the other side. The classroom number is marked on it. There are about 20 rooms by visual inspection.The corridor on the first floor is not connected to the opposite building, it is a closed structure, you can see the head at a glance, and it is not far away when you walk, but Gu Ye still kept an extra eye, and specially wrote down the first room on the left after going downstairs. classroom number.

After walking for a while, Gu Ye immediately realized that something was wrong.

"Wait a minute," Gu Ye asked everyone to stop, and he reconfirmed the door number of the classroom he was in. No, the order of the numbers was confusing.

"The room number on the left after I just went downstairs is 0812," Gu Ye remembered this number very clearly, and it could never be wrong, because it happened to be the date when Qian Fei's accident was broadcast on TV. The sequence of Arabic numerals, but the current serial number is 0814, 0815..."

Everyone was busy looking for the door just now, and didn't notice this detail at all. Gu Ye only paid attention to the classroom number when he reminded him.Everyone didn't believe in evil, so they walked back immediately, wanting to see which classroom had the problem. Unexpectedly, after going back a few classrooms, they found that the number of classrooms decreased from large to small at first, and then after reaching a certain classroom Start increasing from small to large: at first the number sequence was 0814, 0815, 0816, 0817, then suddenly changed to 0817, 0816, 0815, and 0817, which had just been divided, disappeared...

The jumbled room numbers indicate that room numbers were skipped.At this time, there is a huge risk of skipping any classroom, because the classroom that is skipped is likely to be the back door.

Ye Tian immediately said: "Isn't this another ghost hitting the wall! How about we still use the method just now, close our eyes and walk, maybe we will walk out."

Gu Ye shook his head and said, "Not this time..."

The method of closing the eyes to go down the stairs is because they have a direction in their hearts, as long as they walk in that direction.But the problem now is that they don't even know where the back door is in the corridor. Even if they finally reach it, they may miss it because they closed their eyes the whole time.

"Then what should we do?" Ye Tian was discouraged.

Gu Ye thought for a while and said, "We need to find the pattern... Only when we find the pattern can we correct the direction in advance before the order of numbers changes..."

Xiao Ding was a little puzzled. He has never been good at mathematics. Whenever he saw Arabic numerals, he would get dizzy, so he asked, "What does this mean?"

Gu Ye then explained it in a simpler language, "For example, the rule of the number of rooms is that every time the number ending in 0 changes, then if we go along this road now, the number sequence number is 0818, 0819, 0820...0820 ends with 0, then the order of numbers will change after 0820, 0820 disappears, and becomes 0819, 0818, 0817, so we have to go back immediately in the room of 0820, the order of numbers is reversed from before Come here, it becomes 0821, 0822, 0823..."

Xiao Ding finally understood, but he was even more puzzled, "We just walked for a long time, and the numbers increased and decreased, so there is no pattern."

"We need to know four numbers, and then summarize the rules." Gu Ye said, he actually found a little fun in doing Olympiad problems when he was a child.

Everyone moves on, noting the room number each time it changes.The room number they had on hand when they set off was 0820.The first room number to change is 0823, followed by 0825 and 0827...

Only two numbers were found, but Gu Ye didn't leave when he got here.

"Why don't you leave?" Ye Tian asked.

Gu Ye said: "There is no need to look for it anymore, the pattern has already appeared."

There is no point in continuing to go down, the answer is obvious... 2, 3, 5, 7 This is the basic compulsory course of mathematics in the first grade of junior high school - prime number.

Gu Ye stood where he was, building his model in his brain.The classroom number they were in just now is 0820, the first classroom is 0812, and 2 is the first prime number, if the order of the room number numbers at the end of each prime number is changed, then they will never reach the last classroom — 0828.

This classroom that will not appear is the "back door" they are looking for.

After finding the pattern, things finally took shape. According to the method that Gu Ye came up with, everyone immediately turned around and walked back whenever the room numbers ended with 2, 3, 5, 7, or 9.This method really worked, and the confusing classroom numbers began to be arranged in order from small to large.

The time was approaching [-]:[-], and everyone was sweating from walking, especially Ye Tian, ​​who looked back frequently, and was frightened half to death when there was a sign of trouble, for fear that Qian Fei would suddenly follow.

After walking for about 5 minutes, the classroom numbers began to draw to a close: 0825, 0826, 0827... They finally reached the end of the corridor, but a blank sign was hung in the last classroom.

"Is it here?" Ye Tian asked.

Gu Ye was also not sure, so he pulled out the white paper from the transparent frame, and saw that the sign covered by the white paper read - Infirmary.

Ye Tian was so frightened that his legs went limp, "Fuck, shit, shit..."

All the cells in his body refused: "I won't go in! If I go in, I will die, don't you remember?"

The memory of the night has recovered. Gu Ye clearly remembered how he was stuffed into the locker by the shadow. Gu Ye subconsciously touched the back of his neck that was almost broken by the shadow, and said, "Believe it or not!" .”

The infirmary is still furnished, with staplers that have not been put away, hot water bottles that have cooled down, and office chairs that people have just left. The shrubs and flowers in the room, looking suddenly in the unlit room, the tree shadows are magnificent and treacherous, which makes people panic for no reason.

Although Ye Tian didn't want to, but the big troops came in, he would only be more afraid if he stayed outside alone, so he also walked in, looked around, and said: "How can there be any back door here?"

Gu Ye also searched around, saying: "Don't limit your thinking, the back door is not necessarily a door, it is just a medium. It can be a thing, or even a person..."

Gu Ye deliberately said the word "person" with a deep consonant, which sounds very mysterious, but in fact, he just said this on purpose to scare Ye Tian. The back door cannot be an NPC, because the difficulty factor of such an operation is too great.But Ye Tian obviously believed it, his face turned pale with fright, and he trembled: "Gu, Gu Ye, don't scare me..."

Gu Ye ignored Ye Tian, ​​he went to study the window of the infirmary, the window is the closest thing to the image of "door", his first instinct was this window.

The window structure of the infirmary is the same as that of the cafeteria corridor, using tempered glass, and the four corners are sealed with nails.Xiao Ding was simple and rude. He directly picked up a chair in his hand and threw it on the window. The window made a muffled sound, and Xiao Ding bounced away. Not a single scratch was left on the glass.

Gu Ye helped Xiao Ding up, and said: "This should be the same material as the cafeteria windows. It is bulletproof, and even bullets can't penetrate it, let alone you."

So Gu Ye walked around the infirmary again, and finally returned to the familiar locker.

He integrated all the information he knew: on the first night he found the poster of the male singer Qian Fei liked here; It was mentioned that Qian Fei was bullied by his classmates, and was stuffed into a locker to leave a shadow... It was an accident that something appeared once, and it was a coincidence twice, so the third time it was intentional.

The locker was locked. Gu Ye remembered that the key was put on the locker last time. He asked if anyone saw the key, but no one saw it.Gu Ye had no choice but to go back to his old business again, but the keyhole of this lock is the same as the bullnose lock, the groove is relatively flat, and it has been specially treated for anti-theft, so the card cannot be inserted at all.

But this didn't bother Gu Ye. With an idea, he opened the medical box. Although Tan Linshun took almost half of the contents of the medical box, there were still a few tablets of cold medicine scattered here and there.Gu Ye casually took out a board, inserted|inserted it into the gap of the locker, and then swiped along the edge of the locker. The small iron piece stuck below was immediately pushed aside, and the door bounced open.

A light blue fluorescent light was emitted from the locker, like a computer's LCD screen. Gu Ye tried to look inside, but couldn't see anything else.Everyone also looked in, but they were a little uncertain. After all, everyone expected that the back door should be a fancy door carved with dragons and phoenixes, rather than something like a dog hole.

"Is it this one?"

"It can't be wrong," Gu Ye said.

Sophie said, "I can't seem to climb in..."

"Believe me," Gu Ye said, "You are half a head shorter than me, so you can definitely get in."

He doesn't want to share with everyone the harrowing experience he was forced into, asking: "Who goes first?"

The time was a few seconds short of ten o'clock, Ye Tian should have left immediately, but Ye Tian didn't.He was worried that it wasn't something wrong with the back door, so he kept his eyes open and said, "I can't, it's Sophie, ladies first."

Sophie immediately understood that Ye Tian wanted her to test the poison, so she said, "You don't want to snatch it? Qian Fei will come later."

When it came to Qian Fei, Ye Tian was also anxious. He pushed Sophie and said, "Hurry up!"

Sophie didn't bother to argue with him. Anyway, everyone has to go through this hurdle. It doesn't matter if the first one is the last one. It's safer to go early, so she agreed to go first.

There is a short skirt under Sophie's school uniform, and if she wants to enter the cabinet, she must first bend down and put her head in, and then move her lower body in. This posture is too unsightly.So Xiao Ding took off his school uniform jacket and tied it around Sophie's legs.When tied, Xiao Ding apologized to Sophie in a low voice: "Well, I'm sorry, but although I voted for Sun Yue, you two also played with me, we are even, do you agree?"

Sophie didn't know whether to laugh or cry, and said, "Let's talk about it later, if we still see each other."

Gu Ye also pried open a cabinet below for Sophie, and the pop-up cabinet door just served as a pedal under No. 3 cabinet.Sophie had a slender figure. After sticking her head in, her upper body slid in smoothly and disappeared immediately.

After Sophie disappeared, everything was peaceful, there were no screams or calls for help.It was one past ten o'clock. Seeing that Sophie was walking smoothly, Ye Tian immediately began to climb the cabinet. He stuck his head in, but unexpectedly hit the wall of the locker with a "bang", "Damn it!" Ye Tian frightened: "What... what's going on?"

Gu Ye saw that the light blue fluorescence in the cabinet had disappeared. His heart sank, and he replied, "Only one person can go through a back door..."