某省调查乡村交通状况，得到的统计表中列出了任意两村庄间的距离。省政府“畅通工程”的目标是使全省任何两个村庄间都可以实现公路交通（但不一定有直接的公路相连，只要能间接通过公路可达即可），并要求铺设的公路总长度为最小。请计算最小的公路总长度。

TT and FF are … friends. Uh… very very good friends -____-b

FF is a bad boy, he is always wooing TT to play the following game with him. This is a very humdrum game. To begin with, TT should write down a sequence of integers-_-!!(bored).

Then, FF can choose a continuous subsequence from it(for example the subsequence from the third to the fifth integer inclusively). After that, FF will ask TT what the sum of the subsequence he chose is. The next, TT will answer FF’s question. Then, FF can redo this process. In the end, FF must work out the entire sequence of integers.

 The police office in Tadu City decides to say ends to the chaos, as launch actions to root up the TWO gangs in the city, Gang Dragon and Gang Snake. However, the police first needs to identify which gang a criminal belongs to. The present question is, given two criminals; do they belong to a same clan? You must give your judgment based on incomplete information. (Since the gangsters are always acting secretly.)

0维空间的元素是点，这个毋庸置疑。

2个0维空间的元素可以围成一个1维空间的元素，线段。

4个1维空间的元素可以围成一个2维空间的元素，正方形。

6个2维空间的元素可以围成一个3维空间的元素，正方体。

8个3维空间的元素可以围成一个4维空间的元素，超正方体。

……

一个正方形中，有4个（顶）点，4条线段（边），1个正方形。

一个正方体中，有8个（顶）点，12条线段（棱），6个正方形（面），1个正方体。

……

我们的问题是：给出a与b，请求出：在a维空间的元素中，包含着多少个b维空间的元素。答案可能很大，只需要输出它除以1000000007的余数。

 A tree is a well-known data structure that is either empty (null, void, nothing) or is a set of one or more nodes connected by directed edges between nodes satisfying the following properties.
 There is exactly one node, called the root, to which no directed edges point.
Every node except the root has exactly one edge pointing to it.
 There is a unique sequence of directed edges from the root to each node.
 For example, consider the illustrations below, in which nodes are represented by circles and edges are represented by lines with arrowheads. The first two of these are trees, but the last is not.

 In this problem you will be given several descriptions of collections of nodes connected by directed edges. For each of these you are to determine if the collection satisfies the definition of a tree or not.

 Today is Ignatius’ birthday. He invites a lot of friends. Now it’s dinner time. Ignatius wants to know how many tables he needs at least. You have to notice that not all the friends know each other, and all the friends do not want to stay with strangers.
 One important rule for this problem is that if I tell you A knows B, and B knows C, that means A, B, C know each other, so they can stay in one table.
 For example: If I tell you A knows B, B knows C, and D knows E, so A, B, C can stay in one table, and D, E have to stay in the other one. So Ignatius needs 2 tables at least.

 最近xhd正在玩一款叫做FATE的游戏，为了得到极品装备，xhd在不停的杀怪做任务。久而久之xhd开始对杀怪产生的厌恶感，但又不得不通过杀怪来升完这最后一级。现在的问题是，xhd升掉最后一级还需n的经验值，xhd还留有m的忍耐度，每杀一个怪xhd会得到相应的经验，并减掉相应的忍耐度。当忍耐度降到0或者0以下时，xhd就不会玩这游戏。xhd还说了他最多只杀s只怪。请问他能升掉这最后一级吗？

As we all known, xiaoxin is a brilliant coder. He knew palindromic strings when he was only a six grade student at elementry school.

This summer he was working at Tencent as an intern. One day his leader came to ask xiaoxin for help. His leader gave him a string and he wanted xiaoxin to generate palindromic strings for him. Once xiaoxin generates a different palindromic string, his leader will give him a watermelon candy. The problem is how many candies xiaoxin’s leader needs to buy?

Peter has a string $s=s_1s_2…s_n$, let $suff_i=s_is_{i+1}…s_n$ be the suffix start with $i^{th}$ character of $s$. Peter knows the lcp (longest common prefix) of each two adjacent suffixes which denotes as $a_i=lcp(suff_i,suff_{i+1})(1≤i<n)$.

Given the lcp array, Peter wants to know how many strings containing lowercase English letters only will satisfy the lcp array. The answer may be too large, just print it modulo $10^9+7$.

 虽然草儿是个路痴（就是在杭电待了一年多，居然还会在校园里迷路的人，汗~),但是草儿仍然很喜欢旅行，因为在旅途中 会遇见很多人（白马王子，^0^），很多事，还能丰富自己的阅历，还可以看美丽的风景……草儿想去很多地方，她想要去东京铁塔看夜景，去威尼斯看电影，去阳明山上看海芋，去纽约纯粹看雪景，去巴黎喝咖啡写信，去北京探望孟姜女……眼看寒假就快到了，这么一大段时间，可不能浪费啊，一定要给自己好好的放个假，可是也不能荒废了训练啊，所以草儿决定在要在最短的时间去一个自己想去的地方！因为草儿的家在一个小镇上，没有火车经过，所以她只能去邻近的城市坐火车（好可怜啊~）。