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 read() {
  int x = 0, f = 1;
  char ch = getchar();
  while (ch < '0' || ch > '9') {
    if (ch == '-') f = -1;
    ch = getchar();
  }
  while (ch >= '0' && ch <= '9') {
    x = (x << 3) + (x << 1) + (ch ^ 48);
    ch = getchar();
  }
  return x * f;
}
int n, m, v[200005], head[200005], nxt[200005], tree[200005],
    cnt = -1, vis[200005], dep[200005], cf[200005], father[200005], pre[200005];
void add(int a, int b) {
  v[++cnt] = b;
  nxt[cnt] = head[a];
  head[a] = cnt;
}
void dfs(int x, int fa) {
  vis[x] = 1;
  dep[x] = dep[fa] + 1;
  father[x] = fa;
  for (int i = head[x]; i != -1; i = nxt[i]) {
    if (!vis[v[i]]) {
      pre[v[i]] = i;
      tree[i] = 1;
      dfs(v[i], x);
    }
  }
}
void dfs1(int x) {
  vis[x] = 1;
  for (int i = head[x]; i != -1; i = nxt[i]) {
    if (tree[i]) {
      dfs1(v[i]);
      cf[x] += cf[v[i]];
    }
  }
}
vector<int> ans;
int main() {
  memset(head, -1, sizeof(head));
  n = read();
  m = read();
  for (int i = 1; i <= m; i++) {
    int x = read(), y = read();
    add(x, y);
    add(y, x);
  }
  for (int i = 1; i <= n; i++) {
    if (!vis[i]) dfs(i, 0);
  }
  for (int i = 0; i <= cnt; i += 2) {
    if (tree[i] || tree[i + 1]) continue;
    int x = v[i], y = v[i + 1];
    if (dep[x] < dep[y]) swap(x, y);
    cf[x]++;
    cf[y]--;
  }
  memset(vis, 0, sizeof(vis));
  for (int i = 1; i <= n; i++) {
    if (!vis[i]) dfs1(1);
  }
  memset(vis, 0, sizeof(vis));
  for (int i = 0; i <= cnt; i += 2) {
    if (tree[i] || tree[i + 1]) continue;
    int x = v[i], y = v[i + 1];
    if (dep[x] < dep[y]) swap(x, y);
    int ff = 0;
    for (int j = x; j != y; j = father[j]) {
      if (cf[j] != 1) {
        ff = 1;
        break;
      }
    }
    if (ff) continue;
    ans.push_back((i + 2) / 2);
    while (x != y) {
      ans.push_back((pre[x] + 2) / 2);
      x = father[x];
    }
  }
  sort(ans.begin(), ans.end());
  cout << ans.size() << endl;
  for (int i = 0; i < ans.size(); i++) {
    cout << ans[i] << " ";
  }
  return 0;
}
