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 MAXN = 100010, MAXM = 500010;
vector<int> bcc[MAXN];
vector<int> ans[MAXN];
vector<int> ANS;
int low[MAXN], dfn[MAXN];
int head[MAXN], to[MAXM], NEXT[MAXM];
int id[MAXM];
int bccno[MAXN];
int sta[MAXN];
bool iscut[MAXN];
int cnt, top, tot = 1;
int bcccnt;
void make_list(int u, int v, int ID) {
  NEXT[++tot] = head[u], head[u] = tot, to[tot] = v, id[tot] = ID;
}
void tarjan(int u, int f) {
  low[u] = dfn[u] = ++cnt;
  int ch = 0;
  for (int p = head[u]; p; p = NEXT[p]) {
    int v = to[p];
    int e = p;
    if (!dfn[v]) {
      sta[top++] = e;
      ch++;
      tarjan(v, u);
      low[u] = min(low[u], low[v]);
      if (low[v] >= dfn[u]) {
        iscut[u] = 1, bcc[++bcccnt].clear();
        while (1) {
          int x = sta[--top];
          ans[bcccnt].push_back(id[x]);
          if (bccno[to[x ^ 1]] != bcccnt)
            bcc[bcccnt].push_back(to[x ^ 1]), bccno[to[x ^ 1]] = bcccnt;
          if (bccno[to[x]] != bcccnt)
            bcc[bcccnt].push_back(to[x]), bccno[to[x]] = bcccnt;
          if (to[x ^ 1] == u && to[x] == v) break;
        }
      }
    } else if (dfn[v] < dfn[u] && v != f)
      sta[top++] = e, low[u] = min(low[u], dfn[v]);
  }
  if (f < 0 && ch == 1) iscut[u] = 0;
}
int main() {
  int n, m;
  int u, v;
  cin >> n >> m;
  for (int i = 1; i <= m; i++)
    scanf("%d%d", &u, &v), make_list(u, v, i), make_list(v, u, i);
  for (int i = 1; i <= n; i++)
    if (!dfn[i]) tarjan(i, -1);
  for (int i = 1; i <= bcccnt; i++) {
    if (bcc[i].size() == ans[i].size())
      for (int j : ans[i]) ANS.push_back(j);
  }
  cout << ANS.size() << endl;
  for (int i : ANS) cout << i << ' ';
  return 0;
}
