Problem A. Biconnectivity
Statement
You are to write a program that receives a connected undirected graph and finds
all its articulation points, which are the vertices that, if removed,
leave disconnected graph.
Input file format
Input file contains two integers
N and
M.
Vertices are numbered with integer numbers from
1 to
N.
M is the number of edges.
Each of next
M lines contain pair of integers — numbers of vertices
connected by an edge. There are no pairs of equal numbers.
Output file format
Output file must contain integer representing a quantity of articulation
points, followed by numbers of corresponding vertices in arbitrary order.
Constraints
1 ≤ N, M ≤ 100000
Sample tests
No. 
Input file (input.txt ) 
Output file (output.txt ) 
1 
5 6
1 2
1 3
2 3
1 4
1 5
4 5

1 1
