There are $N$ manholes, indexed from $0$ to $N-1$ and $M$ tunnels connecting pairs of them. Valerio's friend Filippo is waiting for him nearby manhole $N-1$, if he can reach it, he will escape safely.
Valerio starts from manhole $0$ and, every minute, he can choose to move to a manhole adjacent to the one he is in or to stay another minute under the same manhole.

Each police patrol guard L ~i~ manholes, indexed from $0$ to <tex> L_{i-1} </tex>. Patrol $i$ is initially guarding manhole H ~i,0~, every minute it moves from manhole H ~i,j~ to manhole <tex>H_{i,j+1}</tex>, after reaching manhole <tex>H_{i,L_i-1}~</tex>, it return to manhole <tex>H_{i,0}</tex> .

Each police patrol guard L ~i~ manholes, indexed from $0$ to L ~i-1~. Patrol $i$ is initially guarding manhole H ~i,0~, every minute it moves from manhole H ~i,j~ to manhole <tex>H_{i,j+1}</tex>, after reaching manhole <tex>H_{i,L_i-1}~</tex>, it return to manhole <tex>H_{i,0}</tex> .

h2. Date de intrare