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;
vector<int> nei[maxn], stk;
pair<int, int> edges[maxn];
int dfn[maxn], ind, low[maxn], sp;
int col[maxn], colors, sz[maxn];
bool check[maxn];
void Tarjan(int root, int pre) {
  dfn[root] = low[root] = ++ind;
  stk.push_back(root);
  int cnt = 0;
  for (int i = 0; i < (int)nei[root].size(); i++) {
    int next = nei[root][i];
    if (next == pre) continue;
    if (!dfn[next]) {
      Tarjan(next, root);
      if (low[next] >= dfn[root]) check[root] = true;
      cnt++;
      low[root] = min(low[root], low[next]);
    } else
      low[root] = min(low[root], dfn[next]);
  }
  if (dfn[root] == low[root]) {
    colors++;
    while (stk.back() != root) {
      col[stk.back()] = colors;
      sz[colors]++;
      stk.pop_back();
    }
    col[stk.back()] = colors;
    sz[colors]++;
    stk.pop_back();
  }
  if (root == sp && cnt > 1) check[root] = true;
  return;
}
set<int> all;
vector<int> ans;
int num[maxn];
int main() {
  int n, m;
  scanf("%d%d", &n, &m);
  for (int i = 1; i <= m; i++) {
    int &u = edges[i].first, &v = edges[i].second;
    scanf("%d%d", &u, &v);
    nei[u].push_back(v);
    nei[v].push_back(u);
  }
  for (int i = 1; i <= n; i++)
    if (!dfn[i]) {
      sp = i;
      Tarjan(i, 0);
    }
  for (int i = 1; i <= colors; i++) all.insert(i);
  for (int i = 1; i <= m; i++) {
    int u = edges[i].first, v = edges[i].second;
    if (col[u] == col[v]) {
      num[u]++;
      num[v]++;
    }
  }
  for (int i = 1; i <= n; i++)
    if (num[i] > 2 && !check[i] && all.count(col[i])) all.erase(col[i]);
  for (int i = 1; i <= m; i++) {
    int u = edges[i].first, v = edges[i].second;
    if (col[u] == col[v] && all.count(col[u])) ans.push_back(i);
  }
  printf("%d\n", (int)ans.size());
  for (int i = 0; i < (int)ans.size(); i++)
    printf("%d%c", ans[i], (i == (int)ans.size() - 1 ? '\n' : ' '));
  if (ans.empty()) puts("");
  return 0;
}
