2 0
 100000 0
 8 9
1 2
2 3
3 4
4 1
5 6
6 7
7 8
8 5
6 8
 2 1
1 2
 11 9
5 9
8 5
11 3
11 1
3 4
7 11
3 1
11 2
7 2
 7 9
7 3
7 4
1 2
2 3
3 1
3 4
4 5
5 6
6 4
 7 5
5 4
7 3
7 1
6 7
3 1
 7 8
1 2
2 3
3 4
4 1
3 5
5 6
6 7
7 3
 6 9
1 2
2 3
1 4
4 2
5 2
5 3
4 5
6 4
6 5
 7 9
1 2
2 4
4 3
3 1
2 3
4 5
5 6
6 7
7 4
 1 0
 6 7
1 2
2 3
3 1
3 4
4 5
5 6
6 4
 4 5
1 2
2 3
3 4
4 1
1 3
 100000 3
99998 99999
99999 100000
100000 99998

0

 0

 4
1 2 3 4 
 0

 6
3 4 6 7 8 9 
 9
1 2 3 4 5 6 7 8 9 
 3
2 3 5 
 8
1 2 3 4 5 6 7 8 
 0

 4
6 7 8 9 
 0

 6
1 2 3 5 6 7 
 0

 3
1 2 3 

#include <bits/stdc++.h>
using namespace std;
const int inf_int = 1e8;
const long long inf_ll = 4e18;
const double pi = 3.1415926535898;
bool debug = 0;
const int MAXN = 2e5 + 100;
const int LOG = 20;
vector<int> g[MAXN];
bool used[MAXN];
int tin[MAXN], fup[MAXN], timer;
stack<pair<int, int> > st;
vector<vector<pair<int, int> > > com;
void dfs(int v, int p) {
  used[v] = 1;
  fup[v] = timer;
  tin[v] = timer++;
  int child = 0;
  for (int to : g[v]) {
    if (to == p) continue;
    if (used[to]) {
      if (tin[to] < fup[v]) {
        fup[v] = tin[to];
        st.push({v, to});
      }
    } else {
      child++;
      st.push({v, to});
      dfs(to, v);
      fup[v] = min(fup[v], fup[to]);
      if (p == -1 && child > 1) {
        vector<pair<int, int> > temp;
        while (st.top() != make_pair(v, to)) {
          temp.push_back(st.top());
          st.pop();
        }
        temp.push_back(st.top());
        st.pop();
        com.push_back(temp);
      }
      if (p != -1 && fup[to] >= tin[v]) {
        vector<pair<int, int> > temp;
        while (st.top() != make_pair(v, to)) {
          temp.push_back(st.top());
          st.pop();
        }
        temp.push_back(st.top());
        st.pop();
        com.push_back(temp);
      }
    }
  }
}
pair<int, int> edge[MAXN];
void solve() {
  int n, m;
  cin >> n >> m;
  for (int i = 1; i <= m; ++i) {
    int a, b;
    cin >> a >> b;
    g[a].push_back(b);
    g[b].push_back(a);
    edge[i] = {a, b};
  }
  for (int i = 1; i <= n; ++i) {
    if (!used[i]) {
      dfs(i, -1);
      if (!st.empty()) {
        vector<pair<int, int> > temp;
        while (!st.empty()) {
          temp.push_back(st.top());
          st.pop();
        }
        com.push_back(temp);
      }
    }
  }
  set<pair<int, int> > ans;
  for (auto a : com) {
    set<int> ver;
    for (auto x : a) {
      ver.insert(x.first);
      ver.insert(x.second);
    }
    if (ver.size() == a.size()) {
      for (auto x : a) {
        ans.insert(x);
      }
    }
  }
  cout << ans.size() << endl;
  for (int i = 1; i <= m; ++i) {
    int a, b;
    tie(a, b) = edge[i];
    if (ans.count({a, b}) || ans.count({b, a})) {
      cout << i << " ";
    }
  }
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  solve();
}
