#include <bits/stdc++.h>
using namespace std;
const int N = 100010;
int k, n, m, x, y;
int low[N], dfn[N], tc;
int st[N], top;
int h[N], t[N << 1], nx[N << 1], num = 1;
int vis[N], cur;
bool b[N << 1];
int a[N], A[N], ncnt;
void Add(int x, int y) {
  t[++num] = y;
  nx[num] = h[x];
  h[x] = num;
}
void Dfs(int x, int y) {
  dfn[x] = low[x] = ++tc;
  for (int i = h[x]; i; i = nx[i])
    if (t[i] != y && !b[i]) {
      b[i] = b[i ^ 1] = 1;
      st[++top] = i;
      int v = t[i];
      if (!dfn[v]) {
        Dfs(v, x);
        low[x] = min(low[x], low[v]);
        if (dfn[x] <= low[v]) {
          int cnt = 0, Top = 0;
          ++cur;
          while (st[top] != i) {
            int x = st[top--];
            if (vis[t[x]] != cur) vis[t[x]] = cur, ++cnt;
            if (vis[t[x ^ 1]] != cur) vis[t[x ^ 1]] = cur, ++cnt;
            a[++Top] = x;
          }
          if (vis[t[i]] != cur) vis[t[i]] = cur, ++cnt;
          if (vis[t[i ^ 1]] != cur) vis[t[i ^ 1]] = cur, ++cnt;
          a[++Top] = i;
          --top;
          if (dfn[x] == low[v] && cnt == Top) {
            for (int i = 1; i <= Top; i++) A[++ncnt] = 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);
  cout << ncnt << endl;
  sort(A + 1, A + ncnt + 1);
  for (int i = 1; i <= ncnt; i++) printf("%d ", A[i] >> 1);
  return 0;
}
