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 = 100010;
int n, m, x, y, low[N], dfn[N], cnt;
int q[N], l, H[N], to[N << 1], nxt[N << 1], tot = 1;
int bl[N], scnt;
bool vis[N << 1];
int a[N], A[N], ans;
void add(int x, int y) {
  to[++tot] = y;
  nxt[tot] = H[x];
  H[x] = tot;
}
void dfs(int x, int y) {
  dfn[x] = low[x] = ++cnt;
  for (int i = H[x]; i; i = nxt[i]) {
    if (to[i] == y || vis[i]) continue;
    vis[i] = vis[i ^ 1] = 1;
    q[l++] = i;
    int v = to[i];
    if (!dfn[v]) {
      dfs(v, x);
      low[x] = min(low[x], low[v]);
      if (dfn[x] <= low[v]) {
        int t, num = 0, bnum = 0;
        ++scnt;
        do {
          t = q[--l];
          if (bl[to[t]] != scnt) bl[to[t]] = scnt, ++num;
          if (bl[to[t ^ 1]] != scnt) bl[to[t ^ 1]] = scnt, ++num;
          a[++bnum] = t;
        } while (t != i);
        cout << "bnum=" << bnum << " num=" << num << endl;
        if (num == bnum)
          for (int i = 1; i <= bnum; ++i) A[++ans] = a[i];
      }
    } else
      low[x] = min(low[x], dfn[v]);
  }
}
int main() {
  scanf("%d%d", &n, &m);
  for (int i = 1; i <= m; ++i) {
    scanf("%d%d", &x, &y);
    add(x, y);
    add(y, x);
  }
  for (int i = 1; i <= n; ++i)
    if (!dfn[i]) dfs(i, 0);
  sort(A + 1, A + ans + 1);
  printf("%d\n", ans);
  for (int i = 1; i <= ans; ++i) printf("%d ", A[i] >> 1);
}
