2 0
 100000 0
 8 9
1 2
2 3
3 4
4 1
5 6
6 7
7 8
8 5
6 8
 2 1
1 2
 11 9
5 9
8 5
11 3
11 1
3 4
7 11
3 1
11 2
7 2
 7 9
7 3
7 4
1 2
2 3
3 1
3 4
4 5
5 6
6 4
 7 5
5 4
7 3
7 1
6 7
3 1
 7 8
1 2
2 3
3 4
4 1
3 5
5 6
6 7
7 3
 6 9
1 2
2 3
1 4
4 2
5 2
5 3
4 5
6 4
6 5
 7 9
1 2
2 4
4 3
3 1
2 3
4 5
5 6
6 7
7 4
 1 0
 6 7
1 2
2 3
3 1
3 4
4 5
5 6
6 4
 4 5
1 2
2 3
3 4
4 1
1 3
 100000 3
99998 99999
99999 100000
100000 99998

0

 0

 4
1 2 3 4 
 0

 6
3 4 6 7 8 9 
 9
1 2 3 4 5 6 7 8 9 
 3
2 3 5 
 8
1 2 3 4 5 6 7 8 
 0

 4
6 7 8 9 
 0

 6
1 2 3 5 6 7 
 0

 3
1 2 3 

#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 10;
stack<int> s;
vector<pair<int, int> > side;
vector<int> graph[N], ans;
bitset<N> went, used;
int dep[N], low[N], t = 0;
void dfs(int now, int from) {
  int l, r;
  map<int, int> m;
  vector<int> v;
  bool f;
  low[now] = dep[now] = ++t;
  went[now] = true;
  for (int i : graph[now])
    if (!used[i]) {
      used[i] = true;
      s.push(i);
      l = side[i].first;
      r = side[i].second;
      if (r == now) swap(l, r);
      if (!went[r]) {
        dfs(r, i);
        low[now] = min(low[now], low[r]);
        if (low[r] >= dep[now]) {
          f = true;
          m.clear();
          v.clear();
          while (s.top() != i) {
            if (m.find(side[s.top()].first) == m.end())
              m.insert({side[s.top()].first, 1});
            else
              m[side[s.top()].first]++;
            if (m.find(side[s.top()].second) == m.end())
              m.insert({side[s.top()].second, 1});
            else
              m[side[s.top()].second]++;
            v.push_back(s.top());
            s.pop();
          }
          if (m.find(side[s.top()].first) == m.end())
            m.insert({side[s.top()].first, 1});
          else
            m[side[s.top()].first]++;
          if (m.find(side[s.top()].second) == m.end())
            m.insert({side[s.top()].second, 1});
          else
            m[side[s.top()].second]++;
          v.push_back(s.top());
          s.pop();
          for (pair<int, int> i : m)
            if (i.second != 2) {
              f = false;
              break;
            }
          if (f)
            for (int i : v) ans.push_back(i);
        }
      } else
        low[now] = min(low[now], dep[r]);
    }
  return;
}
int main() {
  int n, m, l, r;
  scanf("%d%d", &n, &m);
  side.push_back({0, 0});
  for (int i = 1; i <= m; i++) {
    scanf("%d%d", &l, &r);
    graph[l].push_back(i);
    graph[r].push_back(i);
    side.push_back({l, r});
  }
  went.reset();
  used.reset();
  for (int i = 1; i <= n; i++)
    if (!went[i]) {
      s.push(0);
      dfs(i, 0);
    }
  if (ans.empty())
    printf("0\n\n");
  else {
    sort(ans.begin(), ans.end());
    printf("%ld\n%d", ans.size(), ans[0]);
    for (int i = 1; i < ans.size(); i++) printf(" %d", ans[i]);
    printf("\n");
  }
}
