Competitions

# DFS. Articulation points. Bridges

# Articulation Points

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

#### Input

The first line contains two positive integers **n** and **m** (**n** ≤ **20000**, **m** ≤ **200000**) - 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 inegers `b`

, _{i}`e`

(_{i}**1** ≤ `b`

, _{i}`e`

≤ _{i}**n**) - 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.

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