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 = 1e5 + 5;
struct edge {
  int u, v, id;
} stk[N + N];
vector<edge> adj[N];
int n, m, ptr, ui[N], vi[N];
int dfn[N], low[N], used[N], dft;
set<int> ans, in, eg;
void dfs(int u, int p) {
  dfn[u] = low[u] = ++dft;
  for (auto e : adj[u])
    if (!dfn[e.v]) {
      stk[++ptr] = e;
      dfs(e.v, u);
      low[u] = min(low[u], low[e.v]);
    } else {
      if (!used[e.id]) {
        stk[++ptr] = e;
        low[u] = min(low[u], dfn[e.v]);
      }
    }
  if (low[u] == dfn[p]) {
    in.clear();
    eg.clear();
    while (true) {
      eg.insert(stk[ptr].id);
      if (stk[ptr--].u == p) break;
    }
  }
  for (auto v : eg) {
    in.insert(ui[v]);
    in.insert(vi[v]);
    used[v] = 1;
  }
  if (in.size() == eg.size()) {
    for (auto o : eg) ans.insert(o);
  }
}
int main() {
  cin >> n >> m;
  int u, v;
  for (int i = 1; i <= m; i++) {
    cin >> u >> v;
    tie(ui[i], vi[i]) = tie(u, v);
    adj[u].push_back((edge){u, v, i});
    adj[v].push_back((edge){v, u, i});
  }
  for (int i = 1; i <= n; i++)
    if (!dfn[i]) dfs(i, 0);
  cout << ans.size() << '\n';
  for (auto v : ans) cout << v << ' ';
}
