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>
#pragma GCC optimize("O3")
#pragma GCC optimize("Ofast,no-stack-protector")
using namespace std;
function<void(void)> ____ = []() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
};
template <typename T>
vector<T> &operator<<(vector<T> &__container, T x) {
  __container.push_back(x);
  return __container;
}
template <typename T>
ostream &operator<<(ostream &out, vector<T> &__container) {
  for (T _ : __container) out << _ << ' ';
  return out;
}
const int MAXN = 2e5 + 7;
map<pair<int, int>, int> msk;
vector<int> G[MAXN];
stack<pair<int, int> > stk;
int dfn[MAXN], low[MAXN], idx;
vector<int> vec;
void tarjan(int u, int f) {
  dfn[u] = low[u] = ++idx;
  for (int v : G[u]) {
    if (v == f) continue;
    stk.push(make_pair(min(u, v), max(u, v)));
    if (!dfn[v]) {
      tarjan(v, u);
      ((low[u]) = (low[u]) < (low[v]) ? (low[u]) : (low[v]));
      if (low[v] > dfn[u])
        stk.pop();
      else if (low[v] == dfn[u]) {
        pair<int, int> tp;
        vector<pair<int, int> > edge;
        do {
          tp = stk.top();
          stk.pop();
          edge << tp;
        } while (tp != make_pair(min(u, v), max(u, v)));
        vector<int> point;
        for (auto &e : edge) point << e.first << e.second;
        sort(point.begin(), point.end());
        point.erase(unique(point.begin(), point.end()), point.end());
        if (point.size() == edge.size())
          for (auto &e : edge) vec << msk[e];
      }
    } else
      ((low[u]) = (low[u]) < (dfn[v]) ? (low[u]) : (dfn[v]));
  }
}
void solve() {
  int n, m;
  scanf("%d", &n);
  scanf("%d", &m);
  for (int i = 1; i <= m; i++) {
    int u, v;
    scanf("%d", &u);
    scanf("%d", &v);
    G[u] << v;
    G[v] << u;
    msk[pair<int, int>(min(u, v), max(u, v))] = i;
  }
  for (int i = 1; i <= n; i++)
    if (!dfn[i]) tarjan(i, 0);
  sort(vec.begin(), vec.end());
  cout << vec.size() << "\n" << vec << "\n";
}
int main() {
  solve();
  return 0;
}
