Sometimes getting on Wi-Fi can be a problem. But for students at an East China university, it literally is.
The cafeteria at Nanjing University of Aeronautics and Astronautics (NUAA) is giving internet access to those who can decode a complex calculus equation for the password.
Video showing the differential equation has since gone viral, leaving many on social media stumped.
"Dumb as I am, I may as well use my mobile data," wrote Sina Weibo user "sunzhendan."
"I would rather starve," wrote "babazai."
"One super nerd gets it right, and thousands of academic losers are saved," wrote "niuniu" on chouti.com.
The hurdles don't stop there. In NAUU's Xinyuan Library Restaurant, a musical riddle challenges students to convert a written eight-note melody to numbered musical notation.
"The students from NUAA are all super nerds. They love new things. It must be fun for them," said a NUAA teacher.
The school's catering management said the two different problems cater to the expertises of different majors.
"We chose a music notation problem for the Xinyuan Library Restaurant because it has more liberal arts students," said an employee surnamed Ji.
"We chose a math problem for the other cafeteria because it has more engineering students. Many of them have already worked it out," Ji added.
For those that can't hack it, Ji said the answer is as easy as Pi.