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>
#pragma GCC optimize("O2")
using namespace std;
const int N = 1e6 + 10;
const long long mod = 1e9 + 7;
const long long mod2 = 998244353;
const long long inf = 8e18;
const int LOG = 22;
long long pw(long long a, long long b, long long M) {
  return (!b ? 1
             : (b & 1 ? (a * pw(a * a % M, b / 2, M)) % M
                      : pw(a * a % M, b / 2, M)));
}
int n, m, par[N], sz[N], H[N], mark[N], Mn[N];
vector<pair<int, int> > G[N];
int get(int x) { return ((x == par[x]) ? x : par[x] = get(par[x])); }
void unify(int v, int u) {
  v = get(v), u = get(u);
  if (v == u) return;
  if (sz[u] > sz[v]) swap(u, v);
  par[u] = v;
  sz[v] += sz[u];
}
void dfs(int v, int P = 0, int last = 0) {
  Mn[v] = H[v] = H[P] + 1;
  mark[v] = 1;
  for (auto y : G[v]) {
    int u = y.first, id = y.second;
    if (u == P || (mark[u] == 1 && H[u] >= H[v])) continue;
    if (mark[u]) {
      Mn[v] = min(Mn[v], H[u]);
      sz[get(id)]++;
      unify(id, last);
    } else {
      dfs(u, v, id);
      Mn[v] = min(Mn[v], Mn[u]);
      if (Mn[u] <= H[P]) unify(id, last);
    }
  }
}
int main() {
  scanf("%d%d", &n, &m);
  for (int i = 1; i <= m; i++) {
    int a, b;
    scanf("%d%d", &a, &b);
    G[a].push_back(make_pair(b, i));
    G[b].push_back(make_pair(a, i));
  }
  for (int i = 1; i <= m; i++) {
    par[i] = i;
  }
  for (int i = 1; i <= n; i++) {
    if (!mark[i]) {
      dfs(i);
    }
  }
  vector<int> tot;
  for (int i = 1; i <= m; i++) {
    if (sz[get(i)] == 1) tot.push_back(i);
  }
  printf("%d\n", (int)tot.size());
  for (auto x : tot) {
    printf("%d ", x);
  }
  return 0;
}
