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;
int readint() {
  int x = 0, f = 1;
  char s = getchar();
  while (s < '0' || s > '9') {
    if (s == '-') f = -1;
    (s = getchar());
  }
  while (s >= '0' && s <= '9') {
    x = (x << 3) + (x << 1) + (s ^ 48);
    (s = getchar());
  }
  return x * f;
}
struct edge {
  int v, nxt, id;
  edge(){};
  edge(int V, int N, int I) {
    v = V;
    nxt = N;
    id = I;
  }
} e[maxn << 1];
int head[maxn], edge_cnt = -1;
void addedge(int u, int v, int ind) {
  e[++edge_cnt] = edge(v, head[u], ind);
  head[u] = edge_cnt;
  e[++edge_cnt] = edge(u, head[v], ind);
  head[v] = edge_cnt;
}
int dfn_cnt, dfn[maxn], low[maxn];
stack<int> st;
bool vis[maxn << 1];
vector<int> ans;
void tarjan(int u, int fa) {
  dfn[u] = low[u] = ++dfn_cnt;
  for (int i = head[u]; ~i; i = e[i].nxt) {
    int v = e[i].v;
    if (v == fa) continue;
    if (vis[i]) continue;
    vis[i] = vis[i ^ 1] = 1;
    st.push(i);
    if (!dfn[v]) {
      tarjan(v, u);
      low[u] = min(low[u], low[v]);
      if (dfn[u] <= low[v]) {
        set<int> tmp_ver_set;
        set<int> tmp_edge_set;
        tmp_ver_set.insert(u);
        int x;
        do {
          x = st.top();
          st.pop();
          tmp_edge_set.insert(e[x].id);
          tmp_ver_set.insert(e[x].v);
        } while (x != i);
        if (tmp_edge_set.size() == tmp_ver_set.size())
          for (set<int>::iterator it = tmp_edge_set.begin();
               it != tmp_edge_set.end(); it++)
            ans.push_back(*it);
      }
    } else {
      low[u] = min(low[u], dfn[v]);
    }
  }
}
int main() {
  memset(head, -1, sizeof(head));
  int n = readint(), m = readint();
  for (int i = 1; i <= m; i++) {
    int u = readint(), v = readint();
    addedge(u, v, i);
  }
  for (int i = 1; i <= n; i++) {
    if (!dfn[i]) {
      tarjan(i, i);
    }
  }
  sort(ans.begin(), ans.end());
  printf("%d\n", ans.size());
  for (int i = 0; i < ans.size(); i++) {
    printf("%d ", ans[i]);
  }
  return 0;
}
