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 + 10;
int clk, dfn[N], low[N], ve[N], fa[N];
bool onStk[N];
vector<int> ret[N];
stack<int> stk;
vector<pair<int, int> > G[N];
vector<int> ans;
void Mini(int &a, int b) {
  if (b < a) a = b;
}
int dfs(int v, int p = -1) {
  onStk[v] = true;
  fa[v] = p;
  low[v] = dfn[v] = ++clk;
  stk.push(v);
  for (auto e : G[v]) {
    int u = e.first;
    if (u == p) continue;
    if (!dfn[u]) {
      ve[u] = e.second;
      int lv = dfs(u, v);
      Mini(low[v], lv);
      if (lv == dfn[v]) {
        vector<int> vs;
        while (fa[stk.top()] != v) {
          vs.push_back(stk.top());
          stk.pop();
        }
        vs.push_back(stk.top());
        stk.pop();
        bool ok = ret[vs[0]].size() == 1;
        for (int i = 1; ok & i < vs.size(); i++) {
          int u = vs[i];
          if (!ret[u].empty()) ok = false;
        }
        if (ok) {
          for (auto u : vs) {
            ans.push_back(ve[u]);
          }
          ans.push_back(ret[vs[0]][0]);
        }
      }
    } else if (onStk[u]) {
      Mini(low[v], dfn[u]);
      ret[v].push_back(e.second);
    }
  }
  onStk[v] = false;
  return low[v];
}
int main() {
  int n, m;
  scanf("%d%d", &n, &m);
  for (int i = 1; i <= m; i++) {
    int u, v;
    scanf("%d%d", &u, &v);
    G[u].push_back(pair<int, int>(v, i));
    G[v].push_back(pair<int, int>(u, i));
  }
  for (int i = 1; i <= n; i++)
    if (!dfn[i]) dfs(i);
  sort(ans.begin(), ans.end());
  printf("%d\n", ans.size());
  for (auto i : ans) {
    printf("%d ", i);
  }
  puts("");
}
