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

using namespace std;

const int maxn = 300113;
vector<int> gr[maxn];
bool used[maxn];
int tin[maxn];
int fup[maxn];
int times = 0;

map<pair<int, int>, int> d;
map<pair<int, int>, int> kratnrebro;
vector<pair<int, int>> qw;

ifstream in("bridges.in");
ofstream out("bridges.out");

#define mp make_pair
//#define in cin
//#define out cout

void dfs(int v, int p = -1)
{
    used[v] = 1;
    tin[v] = fup[v] = times++;
    for (int i = 0; i < gr[v].size(); i++)
    {
        int to = gr[v][i];
        if (to == p) continue;
        if (used[to])
        {
            fup[v] = min(fup[v], tin[to]);
        }
        else
        {
            dfs(to, v);
            fup[v] = min(fup[v], fup[to]);
            if (fup[to] > tin[v] && kratnrebro[mp(v, to)] == 1)
            {
                pair<int, int> outr = mp(v, to);
                qw.push_back(outr);
            }
        }
    }
}

int main()
{
    int n, m;
    in >> n >> m;
    int ap, bp;
    for (int i = 0; i < m; i++)
    {
        in >> ap >> bp;
        gr[ap].push_back(bp);
        gr[bp].push_back(ap);
        d[mp(ap, bp)] = i + 1;
        d[mp(bp, ap)] = i + 1;
        kratnrebro[mp(ap, bp)] += 1;
        kratnrebro[mp(bp, ap)] += 1;
    }
    for (int i = 1; i <= n; i++)
    {
        if (!used[i])
        {
            dfs(i);
        }
    }
    out << qw.size() << endl;
    for (int i = 0; i < qw.size(); i++)
    {
        out << d[mp(qw[i].first, qw[i].second)] << " ";
    }
}