Ferrying 358 soldiers using two children and a boat

A troop of $358$ soldiers must cross a river. The only boat belongs to two children and can carry either both children or a single adult. How many one-way crossings are needed to get every soldier across, finishing with both children together with the boat?

$1432$. A four-crossing cycle moves one soldier: both children cross, one returns, a soldier crosses, the other child returns. This leaves the children and boat back where they started, so $358$ soldiers need $358\times4=1432$ crossings.