The Exploding Bridge

4 soldiers need to cross a narrow bridge at night which will explode in 18 minutes.

Only 2 can cross at a time, and they only have 1 lantern, so one of them will need to bring it back after each crossing before they make another trip across.

Because of wounds, the slowest man takes 10 minutes to cross the bridge. Another man takes 5 minutes. Another takes 2 minutes, and the fastest man takes 1 minute.

How can they cross the bridge in less than 18 minutes?

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