Four people are traveling in the dark when they arrive at a river. The narrow bridge can accommodate only two people at a time, and the group has only one torch, which must accompany each party that makes a crossing. Persons A, B, C, and D can cross in 1, 2, 5, and 8 minutes, respectively, and any pair of travelers can move only at the pace of the slower person. The torch will go out in 15 minutes. Can they all get safely across?
