Ying tore a page from Dr. Han's notepad, wrote the words "use the little ghost card", and stuck it on the window of Ward No. 4 facing the glass, and then hurriedly took Dr. Han to the elevator for surgery.

The elevator for surgery is more spacious than other passenger elevators, and has a two-way door design. The two walked in quickly, and the elevator door slowly closed. Only then did they find that the interior of the elevator was all covered with graffiti with spray paint.

The spray paint used is highly saturated, resulting in bright and dazzling colors. The graffiti content basically revolves around four graphics of black and red flowers. The specious clown portrait is smiling eerily, and the expression is exactly the same as those of patients with advanced infection.

After Han Xingqian pressed the elevator button and there was no response, he raised his fingertips and touched the spray paint on the four walls, and twisted: "It's not dry yet, we're in trouble."

Ying found that there were some odds and ends in the darkest corner of the elevator, squatted over to examine it carefully, and turned back to Han Xingqian: "Doctor Han, look, there is a golden scale here."

A small golden scale about 30 centimeters long was screwed to the ground, the trays on both sides were empty, and the scale pointer pointed to the "0" in the center.

There are a total of twelve playing cards lined up under the scale, 3 of hearts, 3 of clubs, 3 of diamonds, 4 of hearts, 4 of clubs, 4 of diamonds, 5 of hearts, 5 of clubs, 5 of diamonds, red Peach 6, plum blossom 6, square slice 6.

Ying squatted on the ground and wanted to pick up these cards, but only one of each number could be picked up, and the others were stuck on the ground and could not be moved.

"What a heavy card." Ying muttered, trying to use the communicator to contact Bai Chunian, but since entering the elevator, the signal has become weaker, and the other party has not responded after calling for a long time.

With the hearts 3, 4, 5, and 6 in her hand, Ying tried to put it on the balance. First, she randomly divided the four cards into two piles, and weighed the weights with both hands. 4 and 6 are placed on the two trays of the balance, respectively.

With a crisp sound, the scales tilted sharply to the right.

"Ahhh! Did you make a mistake?" Ying immediately remedied and took the card off the scale, but it was too late, and the elevator began to descend.

Han Xingqian frowned: "There are infected patients below, and we came up from the downstairs."

The elevator stopped on the fourth floor. Before it stopped, the roars of infected patients gathered at the elevator entrance could be heard. Han Xingqian tried his best to hold down the door-close button to prevent the elevator door from opening.

But the door closing key is time-effective, the door will automatically open every time after a period of time, and the door must be released and pressed again to close the door.

About ten seconds later, the elevator door opened a crack. Han Xingqian quickly pressed the door close button again, but the hands of those infected patients were about to reach in. The elevator has a sensor device. Open immediately.

Ying shouted, "Doctor Han turned around and covered his eyes!"

Han Xingqian had already skillfully loaded Ying's pistol. Hearing the little guy say this, he turned his back and raised his sleeves to cover his eyes.

Only two muffled thuds were heard, and two round bombs were thrown from the gap in the elevator. The bombs exploded among the infected people. The strong flash and the slight blasting force drove the infected patients away from the elevator at once.

The J1 differentiation ability of firefly glands is "flash bomb", which can temporarily shield the other party's senses (including those who are blind), and has a certain blasting impact.

The elevator door was temporarily closed again, and the infected patients frantically gathered in front of the elevator door again. A terrifying force slapped the elevator door violently. The huge slamming and gnawing and roaring were only one door away from the two of them.

With cold sweat all over her head, Ying tried to calm down and think with the cards: "Isn't it the weight, then, according to the number? 3 plus 6 equals 4 plus 5..." He tentatively put the four cards back on the balance tray again.

This time, the scales tipped sharply to the left again.

The elevator rose rapidly, not knowing what floor it would stop on, Han Xingqian asked Ying to come over to guard the door, squatted in the corner, picked up the playing cards and weighed it.

Although the appearance of these four cards is the same, the density difference is very large. It can be intuitively felt that the 6 of hearts is the heaviest, and then becomes lighter in turn, and the 3 of hearts is the lightest.

He glanced at the remaining cards stuck to the ground, then placed the 3, 4, and 5 of hearts on the left side of the scale, and the 6 of hearts on the right side of the scale.

The balance swayed from side to side, the shaking amplitude gradually became smaller, and the pointer in the middle gradually stopped at the "0" position.

The elevator button was finally unlocked, Han Xingqian stood up and pressed the button on the top floor.

Ying held Wei Chong, the muzzle of the gun discreetly pointed at the crack of the elevator door, her chest heaved violently, and she asked in a trembling voice, "Okay?"

"Well, it's the equation of adding cubes. You can think of these four numbers as the edge lengths of four cubes of the same density." Han Xingqian lifted the silver lockbox under his feet again, and suddenly a line of sight fell on Yingxiao. On his shiny buttocks, he laughed out loud, "If I don't talk to Xiaobai, you might be able to get scolded less."

Hotaru covered her buttocks in shame, and a sluggish pheromone emanated from her glands.

The elevator stopped at the top floor, and there was still a flight of stairs to go from the rooftop. Ying and Dr. Han cautiously touched the safety door of the stairs and peeped through the door mirror to see what was going on outside the door.

The door mirror seemed to be blocked, and all he could see was a dark red.

"The door is locked. I'll try to open it. Doctor Han, please step back." Ying quickly took out the tool from her backpack, stuck it on the lock and pried it hard.

With a click, the lock was released, and the safety door slowly opened inward.

Ying froze for a moment, and a cold chill poured from her head to her feet.

An infected patient kept looking at the door mirror with one eye closed. After the security door was opened, his face festered, and the corners of his mouth were terribly torn to the point where he smiled.

There were countless infected patients crowded behind him, and the moment he saw Yingying, the corners of his mouth were neatly ripped, revealing a weird and exaggerated smile.

After a few seconds of pause, a large number of infected patients roared and squeezed into the safety gate, grabbed Ying's body with their blood-stained hands, and opened their mouths greedily and frantically to welcome fresh food.

Ying quickly took off her backpack and threw it to Dr. Han who was not close to the security gate. She tried her best to hold on to the security gate, shot the infected patients around Dr. Han with a micro-flush, and shouted at him: "Enter the elevator, Dr. Han quickly hide in!"