eolymp
Competitions

2011 Зимняя Школа, Харьков, День 8, День Виталия Гольдштейна

Articulation Points

The undirected graph is given. Find all its articulation points.

Input

The first line contains two positive integers n and m (n2 * 104, m2 * 105) - the number of vertices and edges respectively.

Each of the next m lines contains the description of an edge. The edge number i is given with two positive integers bi, ei (1bi, ein) - the numbers of the vertices it connects.

Выходные данные

Print in the first line the number b of articulation points in a given graph. In the next b lines print the numbers of the vertices that are articulation points in increasing order.

prb1945.gif

Time limit 3 seconds
Memory limit 128 MiB
Input example #1
9 12
1 2
2 3
4 5
2 6
2 7
8 9
1 3
1 4
1 5
6 7
3 8
3 9
Output example #1
3
1
2
3
Author Vitaly Goldstein
Source Winter School, Kharkov, 2011, Day 9