I need help to solve a Larson's task:
"Lets G is the eventual unoriented connected graph. We will assume that it is the system of tunnels, a fugitive can be hidden in which. Group from S policemen, moving on tunnels, aims to grasp this fugitive which can move with any speed, aiming to avoid catching. It is required to define the least
policemen S, guaranteing catching of fugitive."

Help me, please...