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> h[maxn];
int dfn[maxn], low[maxn];
int n, m, k = 0;
stack<int> s;
int cnt = 0;
struct node {
  int to, nxt, id;
} edge[maxn * 2];
int ecnt = 0;
int head[maxn];
void add(int from, int to, int id) {
  edge[ecnt].to = to;
  edge[ecnt].nxt = head[from];
  edge[ecnt].id = id;
  head[from] = ecnt++;
}
bool iscut[maxn];
void tarjan(int u, int fa) {
  dfn[u] = low[u] = ++k;
  int child = 0;
  for (int i = head[u]; i != -1; i = edge[i].nxt) {
    int v = edge[i].to;
    if (edge[i].id == fa) continue;
    s.push(edge[i].id);
    if (!dfn[v]) {
      child++;
      tarjan(v, edge[i].id);
      low[u] = min(low[u], low[v]);
      if (low[v] >= dfn[u]) {
        cnt++;
        iscut[u] = 1;
        while (true) {
          int x = s.top();
          s.pop();
          h[cnt].push_back(x);
          if (x == edge[i].id) break;
        }
      }
    } else
      low[u] = min(low[u], dfn[v]);
  }
  if (fa == -1 && child < 2) iscut[u] = 0;
}
int x[maxn], y[maxn];
set<int> t;
int indeg[maxn];
bool check(int id) {
  t.clear();
  for (int i = 0; i < h[id].size(); i++) {
    int p = h[id][i];
    t.insert(x[p]);
    t.insert(y[p]);
  }
  return t.size() == h[id].size();
}
int main() {
  scanf("%d%d", &n, &m);
  int u, v;
  for (int i = 1; i <= n; i++) head[i] = -1;
  for (int i = 1; i <= m; i++) {
    scanf("%d%d", &u, &v);
    add(u, v, i);
    add(v, u, i);
    x[i] = u;
    y[i] = v;
  }
  for (int i = 1; i <= n; i++) {
    if (!dfn[i]) tarjan(i, -1);
  }
  vector<int> ans;
  for (int i = 1; i <= cnt; i++) {
    if (check(i)) {
      for (int j = 0; j < h[i].size(); j++) ans.push_back(h[i][j]);
    }
  }
  sort(ans.begin(), ans.end());
  printf("%d\n", ans.size());
  for (int i = 0; i < ans.size(); i++) printf("%d ", ans[i]);
  return 0;
}
