TPCPPLAR - Popular

Given a directed graph G , N vertices and M arcs. 

A node X called "acessible" to Y if there is a path from X to Y

A node X called "popular" if every node Y in V fulfill one of two conditions :

1. X is acessible to Y

2. Y is acessible to X

The Problem :  Given graph G, count the number of popular node.

 

Input

- The first line contain N and M, the number of nodes and arcs (1 <= N <= 150000; 1 <= M <= 300000)

- M next lines, each line contains x and y, there is a arcs connect from x to y.  

 

Output

- First line print number of popular nodes.

- Second line print populars node in increasing order. 

Example

Input:

5 4

1 2

3 2

2 4

4 5

Output:

3

2 4 5


ID RESULT TIME
code...



Được gửi lên bởi:Mew.
Ngày:2014-09-18
Thời gian chạy:1s
Giới hạn mã nguồn:50000B
Memory limit:1536MB
Cluster: Cube (Intel G860)
Ngôn ngữ cho phép:Tất cả ngoại trừ: ASM64 GOSU PERL6 PYPY RUST SED

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2014-10-01 13:43:18 Mew.
Đề bài bị sai, đã được sửa lại :D
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