• 应用
• 登录
• 注册

# P3436 [POI2006]PRO-Professor Szu

• 75通过
• 294提交
• 题目提供者 洛谷OnlineJudge
• 评测方式 云端评测
• 标签 Tarjan 动态规划,动规,dp 拓扑排序 POI 2006 高性能
• 难度 省选/NOI-
• 时空限制 1000ms / 128MB
• 提示：收藏到任务计划后，可在首页查看。

## 题目描述

The Byteotian University is situated in the city of Byteion. Apart from the main building the university owns $n$ ) cottages for its academic staff. The cottages are connected with one-way alleys, however, there could be more than one alley between any two cottages (the alley can also form a loop connecting a building to itself). There are also alleys connecting the cottages to the main building. Byteion has been constructed so that no two alleys intersect in a point different from a cottage or the main building (there can however be bridges or tunnels on alleys). Moreover, each and every alley starts and ends in a cottage or the main building. It is known that a route exists between at least one of the cottages and the main building.

Once upon a time, the Byteotian University fancied to hire a well-known computer science pundit - professor Szu. As most outstanding scientists professor Szu has a certain peculiarity to him: each day he wishes to go to the university using a different route (a route being a sequence of alleys, each starting at the cottage the previous one ended at; the main building and each of the cottages may be visited many times). The professor considers two routes distinct if they differ by at least one alley (the order matters; two different alleys connecting the very same two cottages are considered distinct).

Knowing the diagram of connections help the university in finding a cottage which has the greatest number of different routes to the main building possible (staying in such a cottage professor Szu will spend the longest time working at the university). Should there be more than one such cottage - find all of them. Should there be more than $36\ 500$ possible routes between a certain cottage and the main building we will assume that professor Szu can stay in this particular cottage forever (as he surely cannot live infinitely and $100$ years seems a safe guess).

reads from the standard input the diagram of connections between the cottages of Byteion,determines the cottages which Professor Szu could live the longest time in and the longest possible time of habitation,writes the outcome to the standard output.

n个别墅以及一个主建筑楼，从每个别墅都有很多种不同方式走到主建筑楼，其中不同的定义是（每条边可以走多次，如果走边的顺序有一条不同即称两方式不同）。

询问最多的不同方式是多少，以及有多少个别墅有这么多方式，按照顺序输出别墅编号。

如果最多不同方式超过了36500那么都视作zawsze

## 输入输出格式

输入格式：

The first line of the standard input contains two integers $n$ and $m$ ( $1\le n,m\le 1\ 000\ 000$ ) separated by a single space and denoting the number of cottages and alleys in Byteion, respectively (the cottages are numbered from $1$ to $n$ , and the university main building is denoted by $n+1$ ). In the following lines ( $2$ to $m+1$ ) there are pairs of integers $a_i$ , $b_i$ ( $1\le a_i,b_i\le n+1$ for $1\le i\le m$ ) separated by single spaces and denoting the number of the cottage which the $i$ 'th alley starts at and the number of the cottage which the $i$ 'th alley ends at, respectively.

输出格式：

The first line of the standard output should contain the largest number of days that professor Szu could spend in Byteion or a single word zawsze (i.e. always in Polish) should this number exceed $36\ 500$ days. The second line of the standard output should contain the number of cottages, living in which the professor can stay in Byteion for the amount of time specified in the first line. In the third line of the standard output your programme should write out the numbers of all such cottages, separated by single spaces, and arranged in increasing order. All cottages, which the professor can stay forever in, are considered equal.

## 输入输出样例

输入样例#1： 复制
3 5
1 2
1 3
2 3
3 4
3 4
输出样例#1： 复制
4
1
1
提示
标程仅供做题后或实在无思路时参考。
请自觉、自律地使用该功能并请对自己的学习负责。
如果发现恶意抄袭标程，将按照I类违反进行处理。