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 double g = 10.0, eps = 1e-12;
const int N = 100000 + 10, maxn = 200000 + 10, inf = 0x3f3f3f3f,
          INF = 0x3f3f3f3f3f3f3f3f;
vector<pair<int, int> > v[N];
int dfn[N], low[N];
int ind, iscut[N], n, m;
vector<int> ans;
struct edge {
  int u, v, id;
};
stack<edge> s;
int bcccnt, bccno[N], ed[N];
vector<int> bcc[N], bb[N];
void tarjan(int u, int f) {
  dfn[u] = low[u] = ++ind;
  int ch = 0;
  for (int i = 0; i < v[u].size(); i++) {
    int x = v[u][i].first;
    if (x == f) continue;
    edge e = {u, x, v[u][i].second};
    if (!dfn[x]) {
      s.push(e);
      ch++;
      tarjan(x, u);
      low[u] = min(low[u], low[x]);
      if (low[x] >= dfn[u]) {
        iscut[u] = 1;
        bcccnt++;
        bcc[bcccnt].clear();
        while (1) {
          edge now = s.top();
          s.pop();
          ed[bcccnt]++;
          bb[bcccnt].push_back(now.id);
          if (bccno[now.u] != bcccnt) {
            bcc[bcccnt].push_back(now.u);
            bccno[now.u] = bcccnt;
          }
          if (bccno[now.v] != bcccnt) {
            bcc[bcccnt].push_back(now.v);
            bccno[now.v] = bcccnt;
          }
          if (now.u == u && now.v == x) break;
        }
      }
    } else if (dfn[x] < dfn[u]) {
      s.push(e);
      low[u] = min(low[u], dfn[x]);
    }
  }
  if (f < 0 && ch == 1) iscut[u] = 0;
}
int main() {
  scanf("%d%d", &n, &m);
  for (int i = 1; i <= m; i++) {
    int a, b;
    scanf("%d%d", &a, &b);
    v[a].push_back(make_pair(b, i)), v[b].push_back(make_pair(a, i));
  }
  ind = 0;
  for (int i = 1; i <= n; i++)
    if (!dfn[i]) tarjan(i, -1);
  memset(dfn, 0, sizeof dfn);
  for (int i = 1; i <= bcccnt; i++) {
    if (ed[i] == bcc[i].size() && ed[i]) {
      for (int j = 0; j < bb[i].size(); j++) ans.push_back(bb[i][j]);
    }
  }
  sort(ans.begin(), ans.end());
  printf("%d\n", ans.size());
  for (int i = 0; i < ans.size(); i++) printf("%d ", ans[i]);
  puts("");
  return 0;
}
