#include <bits/stdc++.h>
using namespace std;
const int MAXN = 100010, MAXM = 500010;
vector<int> bcc[MAXN];
vector<int> ans[MAXN];
vector<int> ANS;
int low[MAXN], dfn[MAXN];
int head[MAXN], to[MAXM], NEXT[MAXM];
int id[MAXM];
int bccno[MAXN];
int sta[MAXN];
bool iscut[MAXN];
int cnt, top, tot = 1;
int bcccnt;
void make_list(int u, int v, int ID) {
  NEXT[++tot] = head[u], head[u] = tot, to[tot] = v, id[tot] = ID;
}
void tarjan(int u, int f) {
  low[u] = dfn[u] = ++cnt;
  int ch = 0;
  for (int p = head[u]; p; p = NEXT[p]) {
    int v = to[p];
    int e = p;
    if (!dfn[v]) {
      sta[top++] = e;
      ch++;
      tarjan(v, u);
      low[u] = min(low[u], low[v]);
      if (low[v] >= dfn[u]) {
        iscut[u] = 1, bcc[++bcccnt].clear();
        while (1) {
          int x = sta[--top];
          ans[bcccnt].push_back(id[x]);
          if (bccno[to[x ^ 1]] != bcccnt)
            bcc[bcccnt].push_back(to[x ^ 1]), bccno[to[x ^ 1]] = bcccnt;
          if (bccno[to[x]] != bcccnt)
            bcc[bcccnt].push_back(to[x]), bccno[to[x]] = bcccnt;
          if (to[x ^ 1] == u && to[x] == v) break;
        }
      }
    } else if (dfn[v] < dfn[u] && v != f)
      sta[top++] = e, low[u] = min(low[u], dfn[v]);
  }
  if (f < 0 && ch == 1) iscut[u] = 0;
}
int main() {
  int n, m;
  int u, v;
  cin >> n >> m;
  for (int i = 1; i <= m; i++)
    scanf("%d%d", &u, &v), make_list(u, v, i), make_list(v, u, i);
  for (int i = 1; i <= n; i++)
    if (!dfn[i]) tarjan(i, -1);
  for (int i = 1; i <= bcccnt; i++) {
    if (bcc[i].size() == ans[i].size())
      for (int j : ans[i]) ANS.push_back(j);
  }
  cout << ANS.size() << endl;
  sort(ANS.begin(), ANS.end());
  for (int i : ANS) cout << i << ' ';
  return 0;
}
