#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e5 + 100;
int first[maxn], des[maxn * 2], nxt[maxn * 2], tot;
int cnt_n[maxn], cnt_e[maxn], bcc_no[maxn], bcc_cnt;
int dfn[maxn], low[maxn], dfs_clock;
int st[maxn * 2], top;
vector<int> ans;
vector<int> temp;
int m, n;
inline void addEdge(int x, int y) {
  tot++;
  des[tot] = y;
  nxt[tot] = first[x];
  first[x] = tot;
}
void input() {
  cin >> n >> m;
  for (int i = 0; i < m; i++) {
    int u, v;
    scanf("%d%d", &u, &v);
    addEdge(u, v);
    addEdge(v, u);
  }
}
void dfs(int u, int fa, int Eid) {
  dfn[u] = low[u] = ++dfs_clock;
  for (int t = first[u]; t; t = nxt[t]) {
    int v = des[t];
    if (v == fa) continue;
    if (!dfn[v]) {
      st[top++] = t;
      dfs(v, u, t);
      low[u] = min(low[u], low[v]);
      if (low[v] == dfn[u]) {
        bool ok = true;
        bcc_cnt++;
        temp.clear();
        while (true) {
          int tt = st[--top];
          temp.push_back((tt + 1) / 2);
          if (bcc_no[des[tt]] != bcc_cnt) {
            bcc_no[des[tt]] = bcc_cnt;
          } else {
            ok = false;
          }
          if (tt == t) {
            break;
          }
        }
        if (ok) {
          for (int i = 0; i < temp.size(); i++) {
            ans.push_back(temp[i]);
          }
        }
      }
    } else if (dfn[v] < dfn[u]) {
      st[top++] = t;
      low[u] = min(low[u], dfn[v]);
    }
  }
  if (st[top - 1] == Eid) top--;
}
void solve() {
  for (int i = 1; i <= n; i++) {
    if (!dfn[i]) dfs(i, -1, -1);
  }
  sort(ans.begin(), ans.end());
  cout << ans.size() << endl;
  for (int i = 0; i < ans.size(); i++) {
    printf("%d ", ans[i]);
  }
}
int main() {
  input();
  solve();
  return 0;
}
