#include <iostream>
#include <vector>
#include <set>
#include <algorithm>
#include <map>


using namespace std;

pair <int, int> make_edges(int v1, int v2) {
    if (v1 > v2)
        return make_pair(v2, v1);
    return make_pair(v1, v2);
}

void find_bridges(vector<vector<int>>& graph, map<pair<int, int>, int>& edges, set<int>& result, int v, vector <bool>& used, vector <int>& tin, vector <int>& up, int timer, int p = -1) {
    used[v] = true;
    tin[v] = timer++;
    up[v] = tin[v];
    for (int u = 0; u < graph[v].size(); ++u) {
        if (!used[graph[v][u]]) {
            find_bridges(graph, edges, result, graph[v][u], used, tin, up, timer, v);
            up[v] = min(up[v], up[graph[v][u]]);
        }
        else if (graph[v][u] != p) {
            up[v] = min(up[v], tin[graph[v][u]]);
        }
    }
    if ((p != -1) && (tin[v] == up[v]) && (edges[make_edges(v, p)] != -1))
        result.insert(edges[make_edges(v, p)]);
}

void bridges(vector<vector<int>>& graph, map<pair<int, int>, int>& edges, set<int>& result) {
    vector <bool> used;
    int timer = 0;
    vector<int> tin;
    vector<int> up;
    used.resize(graph.size());
    tin.resize(graph.size());
    up.resize(graph.size());
    for (int i = 0; i < graph.size(); ++i) {
        find_bridges(graph, edges, result, i, used, tin, up, timer);
    }
}
int main() {
    int n, m;
    cin >> n >> m;
    vector < vector<int>> graph(n);
    map<pair<int, int>, int> edges;
    for (int i = 0; i < m; ++i) {
        int firstV, secondV;
        cin >> firstV >> secondV;
        if (edges.find(make_edges(firstV - 1, secondV - 1)) == edges.end())
            edges[make_edges(firstV - 1, secondV - 1)] = i + 1;
        else
            edges[make_edges(firstV - 1, secondV - 1)] = -1;
        graph[firstV - 1].push_back(secondV - 1);
        graph[secondV - 1].push_back(firstV - 1);
    }
    set<int> result;
    bridges(graph, edges, result);
    cout << result.size() << endl;
    for (std::set<int>::iterator i = result.begin(); i != result.end(); ++i)
        cout << *i << endl;
    //system("pause");
    return 0;
}