#include<bits/stdc++.h>
using namespace std;
vector<pair<int, int>> G[500007];
int pre[500007], low[500007], nr, liczba_mostow;
bool w[500007], most[1000007];
void DFS(int a, int p = -1, int to = 0, int k = 0){
  w[a] = 1;
  pre[a] = low[a] = ++nr;
  for(auto i : G[a]){
    tie(to, k) = i;
    if(to == p) continue;
    if(w[to]) low[a] = min(low[a], pre[to]);
    else{
      DFS(to, a);
      low[a] = min(low[a], low[to]);
      if(low[to] > pre[a] && !most[k]){
        most[k] = 1;
        liczba_mostow++;
      }
    }
  }
}
int main(){
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  int n, m;
  cin >> n >> m;
  for(int i = 0, a, b;i < m;i++){
    cin >> a >> b;
    G[a].emplace_back(b, i + 1);
    G[b].emplace_back(a, i + 1);
  }
  DFS(1);
  cout << liczba_mostow << '\n';
  for(int i = 1;i <= m;i++)
    if(most[i])
      cout << i << ' ';
}