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 head[1000005 << 2], nxt[1000005 << 2], to[1000005 << 2], n, m, cnt = -1;
int fa[1000005 << 2], cf[1000005 << 2], dep[1000005 << 2], wfa[1000005 << 2];
bool vis[1000005], Tree[1000005];
void Get(int a, int b) {
  nxt[++cnt] = head[a];
  head[a] = cnt;
  to[cnt] = b;
  nxt[++cnt] = head[b];
  head[b] = cnt;
  to[cnt] = a;
}
void dfs1(int x, int f, int dp) {
  fa[x] = f;
  dep[x] = dp;
  vis[x] = 1;
  for (int i = head[x]; i; i = nxt[i]) {
    int u = to[i];
    if (vis[u]) continue;
    wfa[u] = i;
    Tree[i] = 1;
    dfs1(u, x, dp + 1);
  }
}
void dfs2(int x) {
  vis[x] = 1;
  for (int i = head[x]; i; i = nxt[i]) {
    int u = to[i];
    if (Tree[i]) dfs2(u), cf[x] += cf[u];
  }
}
int ip() {
  int x = 0, w = 0;
  char ch = 0;
  while (!isdigit(ch)) w |= ch == '-', ch = getchar();
  while (isdigit(ch)) x = (x << 1) + (x << 3) + (ch ^ 48), ch = getchar();
  return w ? -x : x;
}
vector<int> ans;
int main() {
  n = ip(), m = ip();
  for (int i = 1; i <= m; i++) {
    int u = ip(), v = ip();
    Get(u, v);
  }
  for (int i = 1; i <= n; i++)
    if (!vis[i]) dfs1(i, 0, 1);
  for (int i = 0; i <= cnt; i += 2) {
    if (Tree[i] || Tree[i + 1]) continue;
    int u = to[i], v = to[i + 1];
    if (dep[u] < dep[v]) swap(u, v);
    cf[u]++, cf[v]--;
  }
  memset(vis, 0, sizeof(vis));
  for (int i = 1; i <= n; i++)
    if (!vis[i]) dfs2(i);
  for (int i = 0; i <= cnt; i += 2) {
    if (Tree[i] || Tree[i + 1]) continue;
    int u = to[i], v = to[i + 1];
    if (dep[u] < dep[v]) swap(u, v);
    int tmp = u;
    bool flag = 0;
    for (; fa[tmp] != v; tmp = fa[tmp]) {
      if (cf[tmp] != 1) {
        flag = 1;
        break;
      }
    }
    if (!flag && cf[tmp] == 1) {
      ans.push_back((i + 2) / 2);
      while (u != v) ans.push_back((wfa[u] + 2) / 2), u = fa[u];
    }
  }
  sort(ans.begin(), ans.end());
  printf("%d\n", ans.size());
  for (int i = 0; i < ans.size(); i++) printf("%d ", ans[i]);
  return 0;
}
