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;
int n, m;
pair<int, int> edg[100100];
vector<int> lis[100100];
bool visit[100100];
bool tre[100100];
int dep[100100];
int val[100100];
int par[100100];
int pi[100100];
int sps[100100][20];
int pps[100100][20];
int dfs(int here, int p) {
  dep[here] = ((~p) ? dep[p] + 1 : 0);
  visit[here] = 1;
  par[here] = p;
  for (int &vi : lis[here]) {
    int there = edg[vi].first + edg[vi].second - here;
    if (!visit[there]) {
      tre[vi] = 1;
      pi[there] = vi;
      val[here] += dfs(there, here);
    } else {
      if (there == p)
        ;
      else if (dep[there] > dep[here]) {
        val[here]--;
      } else
        val[here]++;
    }
  }
  sps[here][0] = val[here];
  pps[here][0] = p;
  return val[here];
}
vector<int> vec;
int main() {
  int i;
  scanf("%d%d", &n, &m);
  for (i = 0; i < m; i++) {
    int a, b;
    scanf("%d%d", &a, &b);
    a--;
    b--;
    lis[a].push_back(i);
    lis[b].push_back(i);
    edg[i] = pair<int, int>(a, b);
  }
  for (i = 0; i < n; i++) {
    if (!visit[i]) dfs(i, -1);
  }
  int j;
  for (j = 1; j < 20; j++) {
    for (i = 0; i < n; i++) {
      pps[i][j] = ((~pps[i][j - 1]) ? pps[pps[i][j - 1]][j - 1] : -1);
    }
    for (i = 0; i < n; i++) {
      sps[i][j] = max(sps[i][j - 1],
                      ((~pps[i][j - 1]) ? sps[pps[i][j - 1]][j - 1] : 0));
    }
  }
  for (i = 0; i < m; i++) {
    if (tre[i]) continue;
    int a = edg[i].first, b = edg[i].second;
    if (dep[a] > dep[b]) swap(a, b);
    int t = dep[b] - dep[a], maxi = 0, cur = b;
    for (j = 0; j < 20; j++) {
      if ((t >> j) & 1) {
        maxi = max(maxi, sps[cur][j]);
        cur = pps[cur][j];
      }
    }
    if (maxi == 1) {
      cur = b;
      while (cur != a) {
        vec.push_back(pi[cur]);
        cur = par[cur];
      }
      vec.push_back(i);
    }
  }
  sort(vec.begin(), vec.end());
  printf("%d\n", vec.size());
  for (int &v : vec) {
    printf("%d ", v + 1);
  }
  return 0;
}
