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;
int n, m, hd[100009], cnt, ind[100009];
struct Edge {
  int to, nxt, i;
} edge[100009 << 1];
int dfn[100009], low[100009], sd, q[100009], sq, ans[100009], sa, lq[100009];
int read();
void add(int u, int v, int i) {
  edge[++cnt] = (Edge){v, hd[u], i};
  hd[u] = cnt;
  edge[++cnt] = (Edge){u, hd[v], i};
  hd[v] = cnt;
}
void Tarjan(int u, int fr, int ufa) {
  dfn[u] = low[u] = ++sd;
  q[++sq] = u;
  lq[sq] = fr;
  for (int i = hd[u], v; i; i = edge[i].nxt)
    if (!dfn[v = edge[i].to]) {
      Tarjan(v, edge[i].i, u);
      low[u] = (low[u]) < (low[v]) ? (low[u]) : (low[v]);
      if (low[v] == dfn[u]) {
        int tsq = sq, sum = 0, mb;
        while (q[tsq + 1] != v) {
          sum += (ind[q[tsq--]] > 0);
          mb = ind[q[tsq + 1]] ? ind[q[tsq + 1]] : mb;
        }
        if (q[sq] == v || sum != 1) continue;
        ans[++sa] = mb;
        while (q[sq + 1] != v)
          if (lq[sq--]) ans[++sa] = lq[sq + 1];
      }
    } else {
      if (v != ufa && dfn[v] < dfn[u]) ind[u] = edge[i].i;
      low[u] = (low[u]) < (dfn[v]) ? (low[u]) : (dfn[v]);
    }
}
int main() {
  n = read(), m = read();
  for (int i = 1, u, v; i <= m; ++i) u = read(), v = read(), add(u, v, i);
  for (int i = 1; i <= n; ++i)
    if (!dfn[i]) Tarjan(i, 0, i);
  sort(ans + 1, ans + 1 + sa);
  printf("%d\n", sa);
  for (int i = 1; i <= sa; ++i) printf("%d ", ans[i]);
  puts("");
  return 0;
}
int read() {
  int x = 0, f = 1;
  char c = getchar();
  while (c > '9' || c < '0') f = (c == '-') ? -1 : f, c = getchar();
  while (c >= '0' && c <= '9') x = x * 10 + c - '0', c = getchar();
  return x * f;
}
