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;
void load() {}
const int N = 1e5 + 123;
int pr[N], dep[N], vis[N], ok[N], lab[N], l[N], r[N];
vector<int> ed[N];
int Findset(int u) { return (lab[u] == u) ? u : lab[u] = Findset(lab[u]); }
void dfs(int u, int p) {
  vis[u] = 1;
  for (int v : ed[u]) {
    if (v == p) continue;
    if (!vis[v])
      pr[v] = u, dep[v] = dep[u] + 1, dfs(v, u);
    else {
      int tmp = u;
      while (dep[tmp] > dep[v]) {
        int l = Findset(tmp), r = Findset(pr[tmp]);
        lab[l] = r;
        ok[r] = max(ok[r], ok[l]);
        if (r != pr[tmp]) ok[r] = 1;
        tmp = r;
      }
    }
  }
  return;
}
void trungtt() {
  int n, m;
  scanf("%d%d", &n, &m);
  for (int i = 1; i <= m; ++i) {
    int u, v;
    scanf("%d%d", &u, &v);
    ed[u].push_back(v);
    ed[v].push_back(u);
    l[i] = u, r[i] = v;
  }
  vector<int> ans;
  for (int i = 1; i <= n; ++i) lab[i] = i, ok[i] = 0;
  for (int i = 1; i <= n; ++i)
    if (!vis[i]) dfs(i, 0);
  for (int i = 1; i <= m; ++i) {
    int u = Findset(l[i]), v = Findset(r[i]);
    if (u == v && ok[u] == 0) ans.push_back(i);
  }
  printf("%d\n", ans.size());
  for (int i : ans) printf("%d ", i);
}
int main() {
  load();
  trungtt();
  return 0;
}
