#include <bits/stdc++.h>
using namespace std;
const int N = 3e5 + 6;
int n, m, num[100005], ncyc = 0, cycIn[100005], result[100005], cnt = 0;
int dd[N], head[N];
vector<pair<int, int> > a[100005];
set<int> In[100005];
int re(int h, int k) {
  if (h == 0) return k;
  if (k == 0) return h;
  dd[h] = 1, dd[k] = 1;
  return (head[h] < head[k] ? h : k);
}
int dfs(int h, int id) {
  int n = a[h].size() - 1, x, res = 0;
  for (int i = 0; i <= n; ++i) {
    if (num[a[h][i].first] >= num[h] - 1) continue;
    if (!num[a[h][i].first]) {
      num[a[h][i].first] = num[h] + 1;
      x = dfs(a[h][i].first, a[h][i].second);
      if (!In[h].count(x)) res = re(res, x);
    } else {
      head[++ncyc] = num[a[h][i].first];
      cycIn[a[h][i].second] = ncyc;
      In[a[h][i].first].insert(ncyc);
      res = re(res, ncyc);
    }
  }
  return (cycIn[id] = res);
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  cin >> n >> m;
  int x, y;
  for (int i = 1; i <= m; ++i) {
    cin >> x >> y;
    a[x].push_back(make_pair(y, i));
    a[y].push_back(make_pair(x, i));
  }
  for (int i = 1; i <= n; ++i) {
    if (!num[i]) num[i] = 2, dfs(i, 0);
  }
  for (int i = 1; i <= m; ++i) {
    if (cycIn[i] && !dd[cycIn[i]]) result[++cnt] = i;
  }
  cout << cnt << '\n';
  for (int i = 1; i <= cnt; ++i) cout << result[i] << ' ';
}
