please, someone explain the test case. i don't get how it is 540.0

Look at this sentence attentively: "One of the passengers has found on the Internet a satellite image of the airport territory taken EXACTLY ONE MINUTE AGO"
In worst case the trundercloud will hang out of airport after 600 seconds the passenger has taken the image. After a minute this value = 540.

Thanks

Edited by author 02.04.2012 23:53