CAPCITY - Capital City

There are N cities in Flatland connected with M unidirectional roads. The cities are numbered from 1 to N. The Flat Circle of Flatland (FCF) wants to set up a new capital city for his kingdom. For security reasons, the capital must be reachable from all other cities of Flatland. FCF needs the list of all candidate cities. You are the chief programmer at FACM (Flat Association for Computing Machinery) responsible for providing the list to FCF as soon as possible.

Input

 

The first line of the input file contains two integers։ 1N≤100,000 and 1M≤200,000. Each of the following M lines contains two integers 1A, B≤N denoting a road from A to B.


Output 


The output file contains an integer denoting the number of candidate cities followed by the list of candidate cities in increasing order.


Example


Input:


4 4

1 2

3 2

4 3

2 1


Output:


2

1 2


Ավելացրեց.Narek Saribekyan
Ամսաթիվ.2010-06-20
Ժամանակի սահմանափակումը.1s-4s
Ծրագրի տեքստի սահմանափակումը.50000B
Memory limit:1536MB
Cluster: Cube (Intel G860)
Լեզուներ.C CSHARP C++ 4.3.2 CPP CPP14 JAVA PAS-GPC PAS-FPC PYTHON3
Աղբյուրը.Armenian TST 2010, Round 2

թաքցնել մեկնաբանությունները
2012-05-31 13:45:51 Andreasyan
Այս խնդիրը դրվել է Հայաստանի դպրոցականների ընտրական մրցույթում 2010 թ.
© Spoj.com. All Rights Reserved. Spoj uses Sphere Engine™ © by Sphere Research Labs.