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;
vector<pair<int, int> > v[100005];
vector<int> scc[100005];
int nscc;
vector<int> stk;
int vis[100005];
int lw[100005];
int t;
pair<int, int> p[100005];
int ok[100005];
void dfs(int a) {
  vis[a] = lw[a] = ++t;
  for (auto it : v[a]) {
    if (!ok[it.second]) {
      ok[it.second] = 1;
      stk.push_back(it.second);
      if (!vis[it.first]) {
        dfs(it.first);
        if (lw[it.first] >= vis[a]) {
          while (stk.back() != it.second) {
            scc[nscc].push_back(stk.back());
            stk.pop_back();
          }
          scc[nscc++].push_back(stk.back());
          stk.pop_back();
        }
        lw[a] = min(lw[a], lw[it.first]);
      } else {
        lw[a] = min(vis[it.first], lw[a]);
      }
    }
  }
}
int main() {
  int n, m;
  scanf("%d %d", &n, &m);
  for (int i = 1; i <= m; i++) {
    int a, b;
    scanf("%d %d", &a, &b);
    p[i] = make_pair((a), (b));
    v[a].push_back(make_pair((b), (i)));
    v[b].push_back(make_pair((a), (i)));
  }
  t = 0;
  nscc = 0;
  for (int i = 1; i <= n; i++) {
    if (!vis[i]) {
      dfs(i);
    }
  }
  int node[100005];
  memset(node, 0, sizeof(node));
  vector<int> ans;
  for (int i = 0; i < nscc; i++) {
    int cnt = 0;
    for (auto it : scc[i]) {
      if (node[p[it].first] != i + 1) {
        cnt++;
        node[p[it].first] = i + 1;
      }
      if (node[p[it].second] != i + 1) {
        cnt++;
        node[p[it].second] = i + 1;
      }
    }
    if (cnt == scc[i].size()) {
      for (auto it : scc[i]) ans.push_back(it);
    }
  }
  sort(ans.begin(), ans.end());
  printf("%d\n", ans.size());
  for (auto it : ans) printf("%d ", it);
}
