## Problem K. Strong connectivity ≡

 Author: StdAlg Time limit: 1 sec Input file: input.txt Memory limit: 8 Mb Output file: output.txt

### Statement

You are to write a program that receives a directed unweighted graph and finds all vertices of its strong-connected component, containing given vertex S.

### Input file format

Input file contains two integers N, M and S. Vertices are numbered with integer numbers from 1 to N. M is the number of arcs. Each of next M lines contain pair of integers — starting and ending vertices of some arc respectively. There is at most one arc connecting two vertices in every direction.

### Output file format

Output file must contain integer number T — amount of vertices in strong-connected component. After that, there must be T integer numbers in ascending order — vertices of compontent themselves.

### Constraints

0 ≤ N, M ≤ 100000.

### Sample tests

No. Input file (input.txt) Output file (output.txt)
1
5 4 1
1 2
2 3
3 1
4 1
3 1 2 3

0.036s 0.008s 15