Leaderboard

A group of four people has to cross a bridge. It is dark, and they have to light the path with a flashlight. No more than two people can cross the bridge simultaneously, and the group has only one flashlight. It takes different time for the people in the group to cross the bridge: Annie crosses the bridge in 1 minute, Bob crosses the bridge in 2 minutes, Caren crosses the bridge in 5 minutes, Dorothy crosses the bridge in 10 minutes. How can the group cross the bridge in 17 minutes?