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 const N = 100000;
vector<pair<int, int> > g[N + 1];
vector<int> an;
int dp[N + 1], mndp[N + 1];
int vis[N + 1];
int V;
void ad(int v, int p = V) {
  if (v == V) return;
  for (int i = 0; i < (int)(g[v].size()); ++i) {
    int u = g[v][i].first;
    if (u == p || (mndp[u] != dp[V] && u != V)) continue;
    an.push_back(g[v][i].second);
    ad(u, v);
    return;
  }
}
bool go(int v, int p = 0) {
  vis[v] = 1;
  mndp[v] = dp[v] = dp[p] + 1;
  bool good = true;
  int cy = 0;
  for (int i = 0; i < (int)(g[v].size()); ++i) {
    int u = g[v][i].first;
    if (u == p) continue;
    if (vis[u] == 2) {
      if (mndp[u] < dp[v]) good = false;
      continue;
    }
    if (vis[u] == 0) {
      bool t = go(u, v);
      if (t && mndp[u] == dp[v]) {
        an.push_back(g[v][i].second);
        V = v;
        ad(u);
      } else if (mndp[u] < dp[v])
        good &= t;
      mndp[v] = min(mndp[v], mndp[u]);
    }
    if (mndp[u] < dp[v]) ++cy;
    if (vis[u] == 1) mndp[v] = min(mndp[v], dp[u]);
  }
  good &= cy <= 1;
  vis[v] = 2;
  return good;
}
int main() {
  int n, m;
  scanf("%d%d", &n, &m);
  for (int i = 1; i < (int)(m + 1); ++i) {
    int a, b;
    scanf("%d%d", &a, &b);
    g[a].push_back(make_pair(b, i));
    g[b].push_back(make_pair(a, i));
  }
  for (int i = 1; i < (int)(n + 1); ++i)
    if (!vis[i]) go(i);
  sort(an.begin(), an.end());
  printf("%d\n", (int)an.size());
  for (int i = 0; i < (int)(an.size()); ++i) {
    if (i) printf(" ");
    printf("%d", an[i]);
  }
  printf("\n");
}
