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 Edge {
  int to, nxt;
} e[N * 2];
int n, m, head[N], cntE = 1, dfn[N], low[N], ids;
int stk[N * 3], tp, col[N], tot;
set<int> ans, nd[N], eg[N];
inline void add(int u, int v) {
  e[++cntE] = (Edge){v, head[u]}, head[u] = cntE;
}
void Tarjan(int u, int f) {
  dfn[u] = low[u] = ++ids;
  for (int i = head[u], v; i; i = e[i].nxt)
    if (!dfn[v = e[i].to]) {
      stk[++tp] = i >> 1, stk[++tp] = u, stk[++tp] = v;
      Tarjan(v, i), low[u] = min(low[u], low[v]);
      if (low[v] >= dfn[u]) {
        ++tot;
        for (;;) {
          int t1, t2;
          nd[tot].insert(t1 = stk[tp--]);
          nd[tot].insert(t2 = stk[tp--]);
          eg[tot].insert(stk[tp--]);
          if (t1 == v && t2 == u) break;
        }
      }
    } else if (dfn[v] < dfn[u] && (i ^ 1) != f) {
      stk[++tp] = i >> 1, stk[++tp] = u, stk[++tp] = v;
      low[u] = min(low[u], dfn[v]);
    }
}
int main() {
  scanf("%d%d", &n, &m);
  for (int i = 1, a, b; i <= m; ++i)
    scanf("%d%d", &a, &b), add(a, b), add(b, a);
  for (int i = 1; i <= n; ++i) Tarjan(i, 0);
  for (int i = 1; i <= tot; ++i)
    if (nd[i].size() == eg[i].size()) ans.insert(eg[i].begin(), eg[i].end());
  printf("%d\n", ans.size());
  for (int i : ans) printf("%d ", i);
  return 0;
}
