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: 1 ≤ N ≤ 100,000 and 1 ≤ M ≤ 200,000. Each of the following M lines contains two integers 1 ≤ A, 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

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

hide comments
2019-07-03 18:59:31
Input-
3 5
3 1
2 1
1 3
1 2
3 2
Output-
3
1 2 3
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
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
2019-05-15 07:21:24
Long implemention !!
2019-03-29 10:59:16
What do we mean by candidate cities
2019-03-23 09:54:59
B_U_T_ful
problem
2019-03-23 08:10:30
badihijat!
2019-03-04 18:27:38
GG easy scc + dfs
2019-02-03 07:30:36
the nodes which are involved in an SCC whose size is > 1 is the answer. Dont forget to sort the answer before submitting ;)
2018-11-25 21:58:36 paras meena
Time constraint for java is not added properly. Converted same TLE java code in C++ and got AC.
-1
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