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 NR = 1e5 + 10;
struct Edge {
  int to, next;
};
int n, m, q;
int a[NR], b[NR];
int gsz = 1, fte[NR];
Edge g[NR << 1];
void addEdge(int x, int y) {
  g[++gsz] = (Edge){y, fte[x]};
  fte[x] = gsz;
}
int now, dfn[NR], low[NR];
stack<int> s;
int tot;
set<int> v_dcc[NR], edge[NR];
set<int> ans;
void tarjan(int x, int in_edge) {
  dfn[x] = low[x] = ++now;
  for (int i = fte[x]; i; i = g[i].next) {
    int y = g[i].to;
    if (i == (in_edge ^ 1)) continue;
    if (dfn[y] != 0) {
      s.push(i);
      low[x] = min(low[x], dfn[y]);
      continue;
    }
    s.push(i);
    tarjan(y, i), low[x] = min(low[x], low[y]);
    if (dfn[x] <= low[y]) {
      tot++;
      while (s.top() != i) {
        int j = s.top();
        s.pop();
        v_dcc[tot].insert(g[j].to);
        v_dcc[tot].insert(g[j ^ 1].to);
        edge[tot].insert(j >> 1);
      }
      s.pop();
      v_dcc[tot].insert(x);
      v_dcc[tot].insert(y);
      edge[tot].insert(i >> 1);
    }
  }
}
int main() {
  scanf("%d%d", &n, &m);
  for (int i = 1, x, y; i <= m; i++)
    scanf("%d%d", &x, &y), addEdge(x, y), addEdge(y, x);
  for (int i = 1; i <= n; i++)
    if (dfn[i] == 0) tarjan(i, 0);
  for (int i = 1; i <= tot; i++)
    if (v_dcc[i].size() == edge[i].size())
      ans.insert(edge[i].begin(), edge[i].end());
  printf("%d\n", ans.size());
  for (int i : ans) printf("%d ", i);
  puts("");
  return 0;
}
