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 int MOD = 1e9 + 7;
const int inf = 1e9 + 3;
const long long INF = long long(3e18) + 3;
int add(int a, int b, int mod = MOD) {
  a += b;
  while (a >= mod) a -= mod;
  while (a < 0) a += mod;
  return a;
}
int mul(int a, int b, int mod = MOD) { return (a * 1LL * b) % mod; }
void setIO(const string& s) {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
}
struct DSU {
  int n;
  int cnt;
  vector<int> P, Rank, Size, cntcyc;
  DSU(int n) : n(n) {
    cnt = n;
    P = Rank = Size = cntcyc = vector<int>(n + 1);
    iota(P.begin(), P.end(), 0);
    fill(Size.begin(), Size.end(), 1);
  }
  int Find(int x) { return x == P[x] ? x : P[x] = Find(P[x]); }
  void Union(int a, int b) {
    a = Find(a), b = Find(b);
    if (a == b) return;
    if (Rank[a] < Rank[b]) swap(a, b);
    P[b] = a;
    if (Rank[a] == Rank[b]) ++Rank[a];
    Size[a] += Size[b];
    --cnt;
  }
  int size(int x) { return Size[Find(x)]; }
};
const int N = 1e5 + 10;
vector<pair<int, int>> adj[N];
int tin[N], timer;
DSU dsu(3e6);
int dfs(int v, int p, int from) {
  int reach = inf;
  tin[v] = ++timer;
  vector<int> cands;
  for (auto& [to, idx] : adj[v]) {
    if (to == p) continue;
    if (tin[to] != 0 && tin[to] > tin[v]) {
      ++dsu.cntcyc[dsu.Find(idx)];
    }
    if (tin[to] != 0 && tin[to] < tin[v]) {
      dsu.Union(idx, from);
      reach = min(reach, tin[to]);
      continue;
    }
    int cur = dfs(to, v, idx);
    if (cur <= tin[p]) {
      dsu.Union(idx, from);
      reach = min(reach, cur);
    }
  }
  return reach;
}
signed main() {
  setIO("input");
  int n, m;
  cin >> n >> m;
  for (int i = 1; i <= m; ++i) {
    int a, b;
    cin >> a >> b;
    adj[a].emplace_back(b, i), adj[b].emplace_back(a, i);
  }
  for (int i = 1; i <= n; ++i) {
    if (tin[i] == 0) dfs(i, 0, 0);
  }
  vector<int> ans;
  for (int i = 1; i <= m; ++i) {
    if (dsu.cntcyc[dsu.Find(i)] == 1) ans.emplace_back(i);
  }
  cout << (int)ans.size() << '\n';
  for (auto& i : ans) cout << i << ' ';
  cout << '\n';
}
