CF962F.Simple Cycles Edges

You are given an undirected graph, consisting of $n$ vertices and $m$ edges. The graph does not necessarily connected. Guaranteed, that the graph does not contain multiple edges (more than one edges between a pair of vertices) or loops (edges from a vertex to itself).

A cycle in a graph is called a simple, if it contains each own vertex exactly once. So simple cycle doesn't allow to visit a vertex more than once in a cycle.

Determine the edges, which belong to exactly on one simple cycle.

给你一个无向图，包含 $n$ 个顶点和 $m$ 条边。该图未必连通。保证图中不包含重边（即任意一对顶点之间至多只有一条边）或自环（即不存在从一个顶点指向其自身的边）。

图中的一个环被称为简单环，当且仅当它恰好经过其自身每个顶点一次。因此，简单环不允许在环中重复访问任一顶点。

请确定所有恰好属于一个简单环的边。

The first line contain two integers $n$ and $m$ $(1 \le n \le 100\,000$, $0 \le m \le \min(n \cdot (n - 1) / 2, 100\,000))$ — the number of vertices and the number of edges.

Each of the following $m$ lines contain two integers $u$ and $v$ ($1 \le u, v \le n$, $u \neq v$) — the description of the edges.

第一行包含两个整数 $n$ 和 $m$（$1 \le n \le 100\,000$，$0 \le m \le \min(n \cdot (n - 1) / 2, 100\,000)$），分别表示顶点数和边数。

接下来的 $m$ 行中，每行包含两个整数 $u$ 和 $v$（$1 \le u, v \le n$，$u \neq v$），表示一条边。

In the first line print the number of edges, which belong to exactly one simple cycle.

In the second line print the indices of edges, which belong to exactly one simple cycle, in increasing order. The edges are numbered from one in the same order as they are given in the input.

第一行输出恰好属于一个简单环的边的数量。

第二行按升序输出恰好属于一个简单环的边的编号。边的编号从 1 开始，顺序与输入中给出的顺序一致。