4 men approach a bridge at night. They have only one flashlight, and in order to cross safely, only 2 people can travel across at a time, holding the flashlight. They can also only travel as fast as the slowest person currently crossing. It takes Jon 1 minute to cross, Dan 2 minutes to cross, Mike 5 minutes to cross, and Al 10 minutes to cross. If they must have the flashlight in order to cross the bridge, what’s the shortest amount of time it would take to get all 4 guys across the bridge?
Difficulty Rating: 10