#include <bits/stdc++.h>
using namespace std;
const int N = 1e6 + 10;
struct Edge {
  int u, v, next, id;
} e[N];
vector<int> ans;
int dfn[N], low[N], stck[N], instack[N], head[N], mark[N];
int scnt, ecnt, m, n, tot, top;
void add_edge(int u, int v, int id) {
  e[ecnt].u = u;
  e[ecnt].v = v;
  e[ecnt].id = id;
  e[ecnt].next = head[u];
  head[u] = ecnt++;
}
void dfs(int u, int fa) {
  dfn[u] = low[u] = ++tot;
  for (int i = head[u]; i >= 0; i = e[i].next) {
    int v = e[i].v;
    if (v == fa) continue;
    if (mark[i]) continue;
    mark[i] = mark[i ^ 1] = 1;
    stck[++top] = i;
    if (!dfn[v]) {
      dfs(v, u);
      low[u] = min(low[u], low[v]);
      if (dfn[u] <= low[v]) {
        set<int> e_set;
        set<int> v_set;
        v_set.insert(u);
        int x;
        do {
          x = stck[top--];
          e_set.insert(e[x].id);
          v_set.insert(e[x].v);
        } while (x != i);
        if (e_set.size() == v_set.size())
          for (set<int>::iterator it = e_set.begin(); it != e_set.end(); it++)
            ans.push_back(*it);
      }
    } else
      low[u] = min(low[u], dfn[v]);
  }
}
int main() {
  memset(head, -1, sizeof(head));
  scanf("%d %d", &m, &n);
  for (int i = 1; i <= n; i++) {
    int u, v;
    scanf("%d %d", &u, &v);
    add_edge(u, v, i);
    add_edge(v, u, i);
  }
  for (int i = 1; i <= m; i++) {
    if (!dfn[i]) dfs(i, i);
  }
  sort(ans.begin(), ans.end());
  printf("%d\n", ans.size());
  for (int i = 0; i < ans.size(); i++) printf("%d ", ans[i]);
  return 0;
}
