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 edg {
  int to, nxt, id;
} e[N << 1];
int cnt = 1, head[N], n, m, dfn[N], low[N], num;
bool vis[N << 1];
stack<int> st;
set<int> ans;
set<int>::iterator it;
void add(int u, int v, int id) {
  cnt++;
  e[cnt].to = v;
  e[cnt].nxt = head[u];
  head[u] = cnt;
  e[cnt].id = id;
}
void tarjan(int u) {
  dfn[u] = low[u] = ++num;
  for (int i = head[u]; i; i = e[i].nxt) {
    int v = e[i].to;
    if (vis[i]) continue;
    vis[i] = vis[i ^ 1] = 1;
    st.push(i);
    if (dfn[v])
      low[u] = min(low[u], dfn[v]);
    else {
      tarjan(v);
      low[u] = min(low[u], low[v]);
      if (low[v] >= dfn[u]) {
        int id = -1;
        set<int> E, V;
        V.insert(u);
        do {
          id = st.top();
          st.pop();
          V.insert(e[id].to);
          E.insert(e[id].id);
        } while (id != i);
        if (E.size() == V.size()) ans.insert(E.begin(), E.end());
      }
    }
  }
}
int main() {
  scanf("%d%d", &n, &m);
  for (int i = 1; i <= m; i++) {
    int u, v;
    scanf("%d%d", &u, &v);
    add(u, v, i);
    add(v, u, i);
  }
  for (int i = 1; i <= n; i++)
    if (!vis[i]) tarjan(i);
  printf("%d\n", (int)ans.size());
  for (it = ans.begin(); it != ans.end(); it++) printf("%d ", *it);
  return 0;
}
