After Farmer John realized that Bessie had installed a "tree-shaped" network among his N (1 <= N <= 10,000) barns at an incredible cost, he sued Bessie to mitigate his losses.

Bessie, feeling vindictive, decided to sabotage Farmer John's network by cutting power to one of the barns (thereby disrupting all the connections involving that barn). When Bessie does this, it breaks the network into smaller pieces, each of which retains full connectivity within itself. In order to be as disruptive as possible, Bessie wants to make sure that each of these pieces connects together no more than half the barns on FJ.

Please help Bessie determine all of the barns that would be suitable to disconnect.

* Line 1: A single integer, N. The barns are numbered 1..N.

* Lines 2..N: Each line contains two integers X and Y and represents a connection between barns X and Y.

* Lines 1..?: Each line contains a single integer, the number (from 1..N) of a barn whose removal splits the network into pieces each having at most half the original number of barns. Output the barns in increasing numerical order. If there are no suitable barns, the output should be a single line containing the word "NONE".

10
1 2
2 3
3 4
4 5
6 7
7 8
8 9
9 10
3 8

3
8

INPUT DETAILS:

The set of connections in the input describes a "tree": it connects all the barns together and contains no cycles.

OUTPUT DETAILS:

If barn 3 or barn 8 is removed, then the remaining network will have one piece consisting of 5 barns and two pieces containing 2 barns. If any other barn is removed then at least one of the remaining pieces has size at least 6 (which is more than half of the original number of barns, 5).

題解：
1.構圖的時候我們可以用鄰接表表示防止MLE(常識), 我很懶直接不要時間的用了vector建議自己寫鄰接表。
2.題目所給一定是個樹n個點n-1條邊，題意是在原樹上找到所有與其相連的所有子樹不大于n/2的節點，按字典序輸出!
3.一次O（n）DFS解決所有問題，邊為無向邊，從任一點開始DFS都可以！按照DFS的原理開始搜索并同時記錄子樹的值。
4.核心代碼: