A group of four people must cross a rickety bridge in the dark of night. No more than two people can cross the bridge at one time, and no one can cross the bridge unless one of the people crossing is holding a lantern. There is only one lantern, so the group decides to cross in this manner:

1. Two people cross.
2. One person carries the lantern back across the bridge.
3. Two people cross.
4. One person carries the lantern back across the bridge.
5. Two people cross.

The four people can cross the bridge at different speeds:
Bill needs 1 minute to get across (one-way).
Gil needs 2 minutes to get across (one-way).
Jill needs 5 minutes to get across (one-way).
Phil needs 10 minutes to get across (one-way).

When two people cross together, they must travel at the speed of the slower of the two people. For example, if Bill and Phil cross together, it will take 10 minutes for the two of them to get across. What is the shortest time required to get all four people safely across the bridge?