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;
struct edge {
  int to, id;
  edge *nxt;
} edges[100000 * 2 + 5];
edge *ecnt, *Adj[100000 + 5];
int n, m, fro[100000 + 5], to[100000 + 5];
int dfn[100000 + 5], low[100000 + 5], tcnt;
int stk[100000 * 2 + 5], stkt, edst[100000 + 5], edstt, edans[100000 + 5],
    edanst;
set<int> poist;
void Init() {
  ecnt = &edges[0];
  tcnt = 0;
}
void AddEdge(int u, int v, int id) {
  edge *p = ++ecnt;
  p->to = v, p->id = id;
  p->nxt = Adj[u];
  Adj[u] = p;
  edge *q = ++ecnt;
  q->to = u, q->id = id;
  q->nxt = Adj[v];
  Adj[v] = q;
}
void Tarjan(int u, int fa) {
  dfn[u] = low[u] = ++tcnt;
  for (edge *p = Adj[u]; p != NULL; p = p->nxt) {
    int v = p->to, id = p->id;
    if (!dfn[v]) {
      stk[++stkt] = p->id;
      Tarjan(v, u);
      low[u] = min(low[u], low[v]);
      if (low[u] >= dfn[u]) {
        int tp;
        edstt = 0;
        poist.clear();
        do {
          tp = stk[stkt--];
          poist.insert(fro[tp]);
          poist.insert(to[tp]);
          edst[++edstt] = tp;
        } while (stkt > 0 && (fro[tp] != fro[id] || to[tp] != to[id]));
        if (edstt == poist.size())
          for (int i = 1; i <= edstt; i++) edans[++edanst] = edst[i];
      }
    } else if (v != fa) {
      if (dfn[u] > dfn[v]) stk[++stkt] = id;
      low[u] = min(low[u], dfn[v]);
    }
  }
}
int main() {
  Init();
  scanf("%d %d", &n, &m);
  for (int i = 1; i <= m; i++) {
    scanf("%d %d", &fro[i], &to[i]);
    AddEdge(fro[i], to[i], i);
  }
  for (int i = 1; i <= n; i++)
    if (dfn[i] == 0) Tarjan(i, -1);
  sort(edans + 1, edans + 1 + edanst);
  printf("%d\n", edanst);
  for (int i = 1; i <= edanst; i++)
    if (i == 1)
      printf("%d", edans[i]);
    else
      printf(" %d", edans[i]);
  printf("\n");
  return 0;
}
