#include <iostream>
#include <fstream>
#include <vector>

using namespace std;

struct edge
{
	int to;
	int number;
	edge(int to_, int number_) : to(to_), number(number_)
	{}
};

bool min(int a, int b)
{
	return a < b ? a : b;
}

vector<vector<edge> > edges;
vector<bool> bridges;
vector<int> colour;
vector<int> enter;
vector<int> ret;
int k;
int time_;

void dfs(int v, int prev_v)
{
	cout << v << endl;
	colour[v] = 1;
	enter[v] = ++time_;
	ret[v] = enter[v];

	int u;
	int number;
	for (size_t i = 0; i < edges[v].size(); i++)
	{
		u = edges[v][i].to;
		if (u == prev_v)
			continue;

		if (colour[u] == 1)
			ret[v] = min(ret[v], enter[u]);
		else
		if (colour[u] == 0)
		{
			dfs(u, v);
			ret[v] = min(ret[v], ret[u]);

			number = edges[v][i].number;
			if (enter[v] < ret[u]) {
				if (!bridges[number])
					k++;
				bridges[edges[v][i].number] = true;
			}
		}
	}
	colour[v] = 2;
}

int main()
{
	ifstream in("bridges.in");
	ofstream out("bridges.out");

	int n, m;
	cin >> n >> m;
	edges.resize(n + 1);
	bridges = vector<bool>(m + 1, false);
	enter.resize(n + 1);
	ret.resize(n + 1);
	colour = vector<int>(n + 1, 0);
	k = 0;
	time_ = 0;

	int u, v;
	for (int i = 1; i <= m; i++)
	{
		cin >> u >> v;
		edges[u].push_back(edge(v, i));
		edges[v].push_back(edge(u, i));
	}

	for (int i = 1; i <= n; i++)
		if (colour[i] == 0)
			dfs(i, 0);

	cout << k << '\n';
	for (int i = 1; i <= m; i++)
		if (bridges[i])
			cout << i << ' ';
	return 0;
}