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 = 1e5 + 5;
struct {
  int v, idx, next;
} e[MAXN * 2];
int cnt_edge, head[MAXN];
inline void add_edge(int u, int v, int idx) {
  e[cnt_edge] = {v, idx, head[u]};
  head[u] = cnt_edge++;
}
int n, m;
int par_edge[MAXN], dep[MAXN];
int clr[MAXN];
struct Edge {
  int u, v, idx;
};
vector<Edge> back_edge;
bool cmp(const Edge &a, Edge &b) { return dep[a.u] < dep[b.u]; }
bool deleted[MAXN];
void dfs(int u, int par) {
  clr[u] = 1;
  for (int i = head[u]; i != -1; i = e[i].next)
    if (e[i].v != par) {
      if (clr[e[i].v] == 1) {
        back_edge.push_back((Edge){e[i].v, u, i});
      } else if (clr[e[i].v] == 0) {
        par_edge[e[i].v] = i;
        dep[e[i].v] = dep[u] + 1;
        dfs(e[i].v, u);
      }
    }
  clr[u] = 2;
}
int ans[MAXN], cnt_ans;
int main() {
  memset(head, 0xff, sizeof(head));
  scanf("%d%d", &n, &m);
  for (int i = 0; i < m; i++) {
    int u, v;
    scanf("%d%d", &u, &v);
    add_edge(u, v, i + 1);
    add_edge(v, u, i + 1);
  }
  dfs(1, 1);
  sort(back_edge.begin(), back_edge.end(), cmp);
  memset(clr, 0xff, sizeof(clr));
  for (int i = 0; i < back_edge.size(); i++) {
    int u = back_edge[i].u, v = back_edge[i].v;
    for (; v != u; v = e[par_edge[v] ^ 1].v) {
      if (clr[par_edge[v] >> 1] != -1) {
        deleted[clr[par_edge[v] >> 1]] = deleted[i] = true;
        break;
      }
      clr[par_edge[v] >> 1] = i;
    }
  }
  for (int i = 0; i < back_edge.size(); i++)
    if (!deleted[i]) {
      int u = back_edge[i].u, v = back_edge[i].v;
      for (; v != u; v = e[par_edge[v] ^ 1].v) {
        ans[cnt_ans++] = e[par_edge[v]].idx;
      }
      ans[cnt_ans++] = e[back_edge[i].idx].idx;
    }
  printf("%d\n", cnt_ans);
  sort(ans, ans + cnt_ans);
  for (int i = 0; i < cnt_ans; i++) printf("%d ", ans[i]);
  printf("\n");
  return 0;
}
