#include <bits/stdc++.h>
using namespace std;
const int N = (int)1e5 + 7;
int n, m;
vector<pair<int, int> > G[N];
vector<int> ans;
int dfn[N], low[N], dfs_clock;
int stk[N], top, estk[N], etop;
void tarjan(int u, int eid) {
  dfn[u] = low[u] = ++dfs_clock;
  stk[++top] = u;
  for (auto &e : G[u]) {
    int v = e.second, id = e.first;
    if (id == eid) continue;
    if (!dfn[v]) {
      estk[++etop] = id;
      tarjan(v, id);
      low[u] = min(low[u], low[v]);
      if (low[v] >= dfn[u]) {
        int pcnt = 0, ecnt = 0;
        while (1) {
          int t = stk[top--];
          pcnt++;
          if (t == v) break;
        }
        pcnt++;
        while (1) {
          int t = estk[etop--];
          ans.push_back(t);
          ecnt++;
          if (t == id) break;
        }
        if (pcnt == 1 || pcnt != ecnt) {
          while (ecnt--) ans.pop_back();
        }
      }
    } else if (dfn[v] < dfn[u]) {
      estk[++etop] = id;
      low[u] = min(low[u], dfn[v]);
    }
  }
}
int main() {
  scanf("%d%d", &n, &m);
  for (int i = 1; i <= m; i++) {
    int u, v;
    scanf("%d%d", &u, &v);
    G[u].push_back(make_pair(i, v));
    G[v].push_back(make_pair(i, u));
  }
  for (int i = 1; i <= n; i++) {
    if (!dfn[i]) {
      tarjan(i, 0);
    }
  }
  sort(ans.begin(), ans.end());
  printf("%d\n", (int)ans.size());
  for (int i = 0; i < ans.size(); i++) {
    printf("%d%c", ans[i], " \n"[i == (int)ans.size() - 1]);
  }
  return 0;
}
