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;
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;
}
