#include <bits/stdc++.h>
using namespace std;
struct edge {
  int a, b, i;
} in[2100005];
vector<edge> v[100005];
vector<int> stk;
unordered_set<int> bcc[100005], bccedge[100005];
int vis[100005], low[100005], clk, bccclk;
bitset<2100005> cnt;
void dfs(int x, int p) {
  vis[x] = low[x] = ++clk;
  for (auto i : v[x])
    if (i.b != p) {
      if (!vis[i.b]) {
        stk.push_back(i.i);
        dfs(i.b, x);
        low[x] = min(low[x], low[i.b]);
        if (vis[x] <= low[i.b]) {
          int a = -1;
          while (a != i.i) {
            a = stk.back();
            stk.pop_back();
            bcc[bccclk].insert(in[a].a);
            bcc[bccclk].insert(in[a].b);
            bccedge[bccclk].insert(a);
          }
          bccclk++;
        }
      } else if (vis[x] > vis[i.b]) {
        low[x] = min(low[x], vis[i.b]);
        stk.push_back(i.i);
      }
    }
}
int main() {
  {
    cin.tie(0);
    ios_base::sync_with_stdio(false);
  };
  int n, m;
  cin >> n >> m;
  for (int i = 1; i <= m; i++) {
    cin >> in[i].a >> in[i].b;
    in[i].i = i;
    v[in[i].a].push_back({in[i].a, in[i].b, i});
    v[in[i].b].push_back({in[i].b, in[i].a, i});
  }
  for (int i = 1; i <= n; i++)
    if (!vis[i]) dfs(i, i);
  for (int i = 0; i < bccclk; i++)
    if (bcc[i].size() == bccedge[i].size()) {
      for (int j : bccedge[i]) cnt[j] = 1;
    }
  cout << cnt.count() << '\n';
  for (int i = 1; i <= m; i++)
    if (cnt[i]) cout << i << ' ';
  return 0;
}
