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