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


hide comments
tanroop: 2019-10-24 20:16:08

Which one is 20th TC. Spojtoolkit is a bit confusing

scolar_fuad: 2019-09-24 08:11:41

Straight forward scc

scolar_fuad: 2019-09-24 07:13:34

what it would be if there exist more than one ssc in a graph

trishala_naman: 2019-07-03 18:59:31

Input-
3 5
3 1
2 1
1 3
1 2
3 2
Output-
3
1 2 3

vjvjain0: 2019-05-28 22:55:16

Used (Kosaraju + dfs) WA on 20
Used (Kosaraju + iteration to count outdegree) AC
Used (Kosaraju + dfs) AC

use this: if(vis[i]) return
instead of: if(!vis[i] && comp[i]!=comp[j])
to get AC using dfs

Last edit: 2019-05-28 22:57:30
nour_massri: 2019-05-15 22:40:04

Weak Test cases my code is giving WA for this test case but it gives AC when submitted !!
Input:
3 3
1 2
1 3
2 3
output:
1
3

Last edit: 2019-05-15 22:52:33
aditya_305: 2019-05-15 07:21:24

Long implemention !!

great_coder1: 2019-03-29 10:59:16

What do we mean by candidate cities

az2019: 2019-03-23 09:54:59

B_U_T_ful
problem

ameernsr: 2019-03-23 08:10:30

badihijat!


Added by:Narek Saribekyan
Date:2010-06-20
Time limit:1s-4s
Source limit:50000B
Memory limit:1536MB
Cluster: Cube (Intel G860)
Languages:All except: NODEJS OBJC PERL6 SQLITE VB.NET
Resource:Armenian TST 2010, Round 2