Coronavirus

Arya is a country with $N$ cities (numbered $1$ through $N$). We may assume that the map of Arya is a tree with $N$ vertices corresponding to the cities, rooted at the city number $1$. The coronavirus has spread all over the world and unfortunately, Arya is infected too. The government is trying to defeat this virus. Their scientists made a medicine which can be used to cure parts of the countr