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>
#pragma GCC optimize("Ofast,unroll-loops,fast-math")
using namespace std;
long long poww(long long a, long long b, long long md) {
  return (!b ? 1
             : (b & 1 ? a * poww(a * a % md, b / 2, md) % md
                      : poww(a * a % md, b / 2, md) % md));
}
const int maxn = 1000 * 100 + 5;
const long long inf = 9223372036854775807;
const long long mod = 1e9 + 7;
int n, m, mark[maxn], s[maxn], ans[maxn], h[maxn], b[maxn], cur[maxn], p[maxn],
    par[maxn];
vector<pair<int, int> > adj[maxn];
pair<int, int> e[maxn];
void sfd(int v) {
  mark[v] = 1;
  for (auto u : adj[v]) {
    if (!mark[u.first]) {
      cur[u.first] = cur[v];
      if (s[u.first] > 1) {
        cur[u.first]++;
      }
      sfd(u.first);
      p[v] += p[u.first];
    } else if (u.first != par[v]) {
      if (cur[v] - cur[u.first]) {
        p[u.first]--;
        p[v]++;
      }
    }
  }
}
void dfs(int v) {
  mark[v] = 1;
  for (auto u : adj[v]) {
    if (!mark[u.first]) {
      h[u.first] = h[v] + 1;
      par[u.first] = v;
      dfs(u.first);
      s[v] += s[u.first];
    } else if (u.first != par[v]) {
      s[v]++;
      s[u.first]--;
    }
  }
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  ;
  cin >> n >> m;
  for (int i = 1; i <= m; i++) {
    int u, v;
    cin >> u >> v;
    e[i] = {u, v};
    adj[u].push_back({v, i});
    adj[v].push_back({u, i});
  }
  for (int i = 1; i <= n; i++) {
    if (!mark[i]) dfs(i);
  }
  for (int i = 1; i <= m; i++) {
    int u = e[i].first, v = e[i].second;
    if (h[u] < h[v]) swap(u, v);
    if (s[u] > 1 && h[u] == h[v] + 1) ans[i] = 1;
  }
  memset(mark, 0, sizeof mark);
  for (int i = 1; i <= n; i++) {
    if (!mark[i]) sfd(i);
  }
  for (int i = 1; i <= m; i++) {
    int u = e[i].first, v = e[i].second;
    if (h[u] < h[v]) swap(u, v);
    if (p[u]) ans[i] = 1;
  }
  vector<int> ANS;
  for (int i = 1; i <= m; i++)
    if (!ans[i]) ANS.push_back(i);
  cout << (long long)(ANS).size() << endl;
  for (int i = 0; i < (long long)(ANS).size(); i++) cout << ANS[i] << " ";
}
