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You're in a group of people going for an internship in a remote mountain lab. By mistake you pulled a lever with a skull just out of curiosity and it released some zombies. So you and your group had to run.
The janitor, the lab assistant, the professor and you escaped to a bridge near by. However, the bridge could only take the weight of two persons at a time, otherwise it would collapse.
You know that you take 1 minute to crossover the bridge, as for the assistant takes 2 minutes, the janitor takes 5 minutes and the professor takes a whole 10 minutes.
Its dark and you cannot see more than a small range of space provided by your torch. Those who are without the torch remain quiet and still.
The zombies are coming in about 17 minutes.
Now the puzzle is to find a solution so that you can escape from the zombies and collapse the bridge before they arrive there.