#include <bits/stdc++.h>
#include <fstream>

using namespace std;

vector < vector <int> > g, num;
vector <int> used, tin, tup;
set <int> ans, ans2;

int timer = 0;
void dfs(int v, int predok, int nomer){
    timer++;
    used[v] = 1;
    tin[v] = timer;
    tup[v] = timer;
    for (int i = 0; i < g[v].size(); i++){
        int to = g[v][i];
        if (used[to] == 0){
            dfs(to, v, num[v][i]);
            tup[v] = min(tup[v], tup[to]);
        }
        else if (nomer != num[v][i]){
            tup[v] = min(tup[v], tin[to]);
        }
//            if (check.count({predok, i}) > 1 || check.count({i, predok}) > 1){
//                nr = -15;
//            }
    }
    if (tup[v] > tin[predok] && predok != -1){
        ans.insert(nomer);
    }
}

void dfs2(int v){
    used[v] = 1;
    for (int i = 0; i < g[v].size(); i++){
        int to = g[v][i];
        if (used[to] == 0){
            if (ans.count(num[v][i]) && num[v][i] != - 1){
                //cout << num[v][i] << endl;
                ans2.insert(num[v][i]);
            }
            dfs2(to);
        }
    }
}

int main(){
   // freopen("bridges.in", "r", stdin);
   // freopen("bridges.out", "w", stdout);
    int n, m, x, y;
    cin >> n >> m;
    g.resize(n);
    used.resize(n, 0);
    tin.resize(n);
    tup.resize(n);
    num.resize(n);
    for (int i = 0; i < m; i++){
        cin >> x >> y;
        x--;
        y--;
        g[x].push_back(y);
        g[y].push_back(x);
        num[x].push_back(i + 1);
        num[y].push_back(i + 1);
//        check.insert({x, y});
//        check.insert({y, x});
    }
    //cout<<"input correct"<<endl;
    dfs(0, -1, -1);
    used.assign(n, 0);
    dfs2(0);
    cout << ans2.size() << endl;
    for (set<int>::iterator it = ans2.begin(); it != ans2.end(); ++it) {
        cout << *it << " ";
    }
}