#include <bits/stdc++.h>
using namespace std;
const int N = 100010, M = 200010;
int h[N], e[M], ne[M], idx;
int dfn[N], low[N], bj[N], stk[M], belong[M], isCut[N], num[N], mark[M];
int bccnum, tt = -1, indx, enums;
int n, m, x, y;
pair<int, int> edges[M];
vector<int> v[N], ans;
void add(int a, int b) { e[idx] = b, ne[idx] = h[a], h[a] = idx++; }
void tarjan(int u, int father) {
  dfn[u] = low[u] = ++indx;
  int child = 0;
  for (int i = h[u]; ~i; i = ne[i]) {
    int v = e[i];
    if (mark[i]) continue;
    mark[i] = mark[i ^ 1] = 1;
    stk[++tt] = i;
    if (!dfn[v]) {
      child++;
      tarjan(v, u);
      low[u] = min(low[u], low[v]);
      if (dfn[u] <= low[v]) {
        isCut[u] = 1;
        bccnum++;
        for (;;) {
          int j = stk[tt--];
          if (bj[e[j]] != bccnum) {
            bj[e[j]] = bccnum;
            num[bccnum]++;
            edges[++enums] = {e[j], bccnum};
          }
          if (bj[e[j ^ 1]] != bccnum) {
            bj[e[j ^ 1]] = bccnum;
            num[bccnum]++;
            edges[++enums] = {e[j ^ 1], bccnum};
          }
          belong[(j >> 1) + 1] = bccnum;
          if (i == j) break;
        }
      }
    } else
      low[u] = min(low[u], dfn[v]);
  }
  if (u == father && child < 2) isCut[u] = 0;
}
int main() {
  memset(h, -1, sizeof h);
  scanf("%d%d", &n, &m);
  for (int i = 1; i <= m; i++) {
    scanf("%d%d", &x, &y);
    add(x, y);
    add(y, x);
  }
  for (int i = 1; i <= n; i++)
    if (!dfn[i]) tarjan(i, i);
  for (int i = 1; i <= m; i++) v[belong[i]].push_back(i);
  for (int i = 1; i <= bccnum; i++)
    if (v[i].size() == num[i])
      for (auto x : v[i]) ans.push_back(x);
  sort(ans.begin(), ans.end());
  cout << ans.size() << endl;
  for (auto x : ans) cout << x << " ";
  return 0;
}
