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 = 100005, MAXM = 100005;
struct Graph {
  struct AdjEdge {
    int v, id;
    AdjEdge *nxt;
  } edges[MAXM * 2], *adj[MAXN], *edges_it;
  void Clear() {
    memset(adj, 0, sizeof adj);
    edges_it = edges;
  }
  void AddEdge(int u, int v, int i) {
    edges_it->v = v;
    edges_it->id = i;
    edges_it->nxt = adj[u];
    adj[u] = edges_it++;
  }
};
int n, m;
Graph G;
bool ans[MAXM];
int dfn[MAXN], low[MAXN], dfc;
int stk[MAXN], tp;
int blkid[MAXN], blkc;
void tarjan(int u, int fa = 0) {
  low[u] = dfn[u] = ++dfc;
  stk[++tp] = u;
  for (Graph::AdjEdge *e = G.adj[u]; e; e = e->nxt) {
    int v = e->v;
    if (v == fa) continue;
    if (!dfn[v]) {
      tarjan(v, u);
      low[u] = min(low[u], low[v]);
      if (low[v] >= dfn[u]) {
        blkc++;
        int tmp = tp;
        do {
          blkid[stk[tp]] = blkc;
          tp--;
        } while (stk[tp + 1] != v);
        blkid[u] = blkc;
        int cnt = 0;
        stk[++tmp] = u;
        for (int i = tp + 1; i <= tmp; i++)
          for (Graph::AdjEdge *d = G.adj[stk[i]]; d; d = d->nxt)
            cnt += (blkid[d->v] == blkc);
        if (cnt == (tmp - tp) * 2) {
          for (int i = tp + 1; i <= tmp; i++)
            for (Graph::AdjEdge *d = G.adj[stk[i]]; d; d = d->nxt)
              if (blkid[d->v] == blkc) ans[d->id] = true;
        }
      }
    } else
      low[u] = min(low[u], dfn[v]);
  }
}
int main() {
  scanf("%d%d", &n, &m);
  G.Clear();
  for (int i = 1; i <= m; i++) {
    int u, v;
    scanf("%d%d", &u, &v);
    G.AddEdge(u, v, i);
    G.AddEdge(v, u, i);
  }
  tarjan(1);
  blkc++;
  int tmp = tp;
  do {
    blkid[stk[tp]] = blkc;
    tp--;
  } while (tp);
  int cnt = 0;
  for (int i = tp + 1; i <= tmp; i++)
    for (Graph::AdjEdge *d = G.adj[stk[i]]; d; d = d->nxt)
      cnt += (blkid[d->v] == blkc);
  if (cnt == (tmp - tp) * 2) {
    for (int i = tp + 1; i <= tmp; i++)
      for (Graph::AdjEdge *d = G.adj[stk[i]]; d; d = d->nxt)
        if (blkid[d->v] == blkc) ans[d->id] = true;
  }
  cnt = 0;
  for (int i = 1; i <= m; i++) cnt += ans[i];
  printf("%d\n", cnt);
  for (int i = 1; i <= m; i++)
    if (ans[i]) printf("%d ", i);
  puts("");
  return 0;
}
