#include <bits/stdc++.h>
using namespace std;
struct Edge {
  int v, id;
};
set<int> Ans;
vector<Edge> G[100000 + 5];
int cnt;
stack<int> Node;
bool vis[100000 + 5];
int dfn[100000 + 5], Low[100000 + 5];
void Tarjan(int u, int fa) {
  Node.push(u);
  dfn[u] = Low[u] = ++cnt;
  for (auto e : G[u]) {
    int v = e.v;
    if (!dfn[v]) {
      Tarjan(v, u);
      Low[u] = min(Low[u], Low[v]);
      if (Low[v] >= dfn[u]) {
        set<int> E;
        vector<int> tmp;
        do {
          vis[Node.top()] = 1;
          tmp.push_back(Node.top());
          Node.pop();
        } while (!vis[v]);
        tmp.push_back(u);
        for (int u : tmp)
          for (auto e : G[u])
            if (vis[e.v]) E.insert(e.id);
        if (E.size() == tmp.size()) Ans.insert(E.begin(), E.end());
        for (int i : tmp) vis[i] = 0;
      }
    } else if (v != fa)
      Low[u] = min(Low[u], dfn[v]);
  }
}
int main() {
  int N, M;
  scanf("%d%d", &N, &M);
  for (int i = 1; i <= M; i++) {
    int u, v;
    scanf("%d%d", &u, &v);
    G[u].push_back({v, i});
    G[v].push_back({u, i});
  }
  for (int i = 1; i <= N; i++)
    if (!dfn[i]) Tarjan(i, -1);
  printf("%d\n", Ans.size());
  for (auto i : Ans) printf("%d ", i);
}
