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;
int n;
int m;
vector<int> v[100002];
int dep[100002];
int ord;
int star[100002];
int linkk[100002];
bool use[100002];
vector<pair<int, int> > stk;
vector<vector<pair<int, int> > > vv;
inline void dfs(int b, int pr = -1, int d = 0) {
  use[b] = true;
  dep[b] = d;
  star[b] = ord;
  linkk[b] = ord;
  ord++;
  for (int go : v[b]) {
    if (go == pr) {
      continue;
    }
    if (use[go]) {
      linkk[b] = min(linkk[b], star[go]);
    } else {
      int pr = stk.size();
      dfs(go, b, d + 1);
      linkk[b] = min(linkk[go], linkk[b]);
      if (pr != stk.size()) {
        if (linkk[stk.back().second] == star[b]) {
          vv.push_back(vector<pair<int, int> >());
          while (stk.size() != pr) {
            vv.back().push_back(stk.back());
            stk.pop_back();
          }
        }
      }
    }
  }
  if (linkk[b] != star[b]) {
    for (int go : v[b]) {
      if (dep[b] > dep[go]) {
        stk.push_back(make_pair(go, b));
      }
    }
  }
}
map<pair<int, int>, int> mp;
set<int> s;
set<int> ans;
int main() {
  cin >> n >> m;
  for (int i = 0; i < m; i++) {
    int a, b;
    scanf("%d%d", &a, &b);
    a--;
    b--;
    v[a].push_back(b);
    v[b].push_back(a);
    mp[make_pair(a, b)] = i + 1;
    mp[make_pair(b, a)] = i + 1;
  }
  dfs(0);
  for (int i = 0; i < vv.size(); i++) {
    s.clear();
    for (int j = 0; j < vv[i].size(); j++) {
      s.insert(vv[i][j].first);
      s.insert(vv[i][j].second);
    }
    if (s.size() == vv[i].size()) {
      for (int j = 0; j < vv[i].size(); j++) {
        ans.insert(mp[vv[i][j]]);
      }
    }
  }
  cout << ans.size() << endl;
  bool ng = false;
  for (auto el : ans) {
    if (ng) {
      printf(" ");
    }
    ng = true;
    printf("%d", el);
  }
  puts("");
  return 0;
}
