#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);
        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);
}
