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 = 200005;
int vis[N];
vector<pair<int, int> > g[N];
int del[N];
int dsu[N], cid;
int fa(int x) { return x == dsu[x] ? x : dsu[x] = fa(dsu[x]); }
void join(int a, int b) {
  a = fa(a), b = fa(b);
  del[a] = del[b] = 1;
  dsu[a] = b;
}
int mark[N], p[N], peid[N];
void back(int st, int en) {
  while (st != en) {
    int eid = peid[st];
    if (!mark[eid])
      mark[eid] = cid;
    else
      join(mark[eid], cid);
    int tmp = p[st];
    p[st] = en;
    st = tmp;
  }
}
int v2[N];
void dfs(int u) {
  vis[u] = 1;
  int v, eid;
  for (auto x : g[u]) {
    tie(v, eid) = x;
    if (v2[eid]) continue;
    v2[eid] = 1;
    if (vis[v]) {
      mark[eid] = ++cid;
      dsu[cid] = cid;
      back(u, v);
      continue;
    }
    p[v] = u;
    peid[v] = eid;
    dfs(v);
  }
}
int main() {
  int n, m;
  scanf("%d %d", &n, &m);
  for (int i = 0; i < m; i++) {
    int a, b;
    scanf("%d %d", &a, &b);
    g[a].emplace_back(b, i);
    g[b].emplace_back(a, i);
  }
  for (int i = 1; i <= n; i++)
    if (!vis[i]) dfs(1);
  vector<int> ans;
  for (int i = 0; i < m; i++)
    if (mark[i] && !del[fa(mark[i])]) ans.push_back(i);
  printf("%d\n", int(ans.size()));
  for (int x : ans) printf("%d ", x + 1);
  printf("\n");
}
