Cows have assembled from around the world for a massive gathering. There are N cows, and N-1 pairs of cows who are friends with each other. Every cow knows every other cow through some chain of friendships.

They had great fun, but the time has come for them to leave, one by one. They want to leave in some order such that as long as there are still at least two cows left, every remaining cow has a remaining friend. Furthermore, due to issues with luggage storage, there are M pairs of cows (a_i, b_i) such that cow a_i must leave before cow b_i. Note that the cows a_i and b_i may or may not be friends.

Help the cows figure out, for each cow, whether she could be the last cow to leave. It may be that there is no way for the cows to leave satisfying the above constraints.

Problem credits: Dhruv Rohatgi

#4083 upload - done - how_to_reg - stop_circle Grading on hold

The Cow Gathering timer 2s memory 512MB

#4083
Grading on hold

The Cow Gathering 2s 512MB