Given a undirected graph with $N$ vertices and $M$ edges. $i$-th edge is $(a _ i, b _ i)$. This graph may not be simple but never has a self-loop.
Decompose this graph into biconnected components and output their vertex sets.
A biconnected component is a maximal biconnected subgraph.
$N$ $M$
$a _ 0$ $b _ 0$
$a _ 1$ $b _ 1$
:
$a _ {M-1}$ $b _ {M-1}$
Print the number of biconnected components $K$ in the first line.
Following $K$ lines, print as follows. $l$ is the number of vertices of biconnected components and $v _ i$ is an vertex index.
$l$ $v _ 0$ $v _ 1$ ... $v _ {l-1}$
If there is multiple solutions, print any of them.
4 5 0 3 0 1 3 0 2 1 2 3
1 4 0 1 2 3
10 12 0 6 0 8 1 2 1 6 2 6 3 6 3 9 4 9 4 7 5 6 5 9 6 8
5 3 0 6 8 3 1 2 6 4 3 5 6 9 2 4 7 2 4 9
5 3 0 1 1 0 0 1
4 2 0 1 1 2 1 3 1 4
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