#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;
int n, m, x, y;
vector<vector<pair<int, int>>> g;
int used[30001];
int up[30001];
int deep[30001];
vector<int> ans;

void dfs(int a, int d, int pr, int edge) {
    deep[a] = d;
    used[a] = 1;
    for (auto to : g[a]) {
        if (used[to.first] == 0) {
            dfs(to.first, d + 1, a, to.second);
            up[a] = min(up[a], up[to.first]);
        }
        if (used[to.first] == 1 && to.first != pr) {
            up[a] = min(up[a], deep[to.first]);
        }
    }
    if (deep[a] <= up[a] && edge != -1) {
        ans.push_back(edge);
    }
    used[a] = 2;
}

int main() {
    cin >> n >> m;
    g.resize(n);
    for (int i = 0; i < m; ++i) {
        cin >> x >> y;
        --x; --y;
        g[x].push_back({y, i});
        g[y].push_back({x, i});
    }
    for (int i = 0; i < n; ++i) {
        deep[i] = -1;
        up[i] = 1e9;
    }
    for (int i = 0; i < n; ++i) {
        if (used[i] == 0) {
            dfs(i, 0, -1, -1);
        }
    }
    sort(ans.begin(), ans.begin() + ans.size());
    cout << ans.size() << endl;
    for (auto an : ans) {
        cout << an + 1 << " ";
    }
    return 0;
}