Broken Computer Who is Responsible?

Friend 1 and Friend 2 are on the top floor of a builing. Friend 1 swiftly takes 2's computer away and balances it on a nearby ledge. He calls over, "come get your laptop!" Friend 2 is completely aware of where his computer is. He does nothing, although his computer is in a dangerous position. 1 moves away from the computer, still balanced on the ledge. 2 knows that 1 is not near the computer and is not holding it for him. Friend 2 does not ask 1 to recover the computer. 2 does not go to get his own computer. after about 2 minutes of no one doing anything, the computer suddenly falls. The screen is now broken. Who should pay for the repair/new computer? What is the percentage of blame for each of these two people?