#include <bits/stdc++.h>
using namespace std;
const int N = 100010;
int n, m, h[N], num = 1, dfn[N], low[N], timer = 0, bcc = 0, sz[N], ans = 0;
bool f[N], used[N];
struct edge {
  int to, next;
};
edge data[N << 1];
vector<int> a[N];
stack<int> vstack;
stack<int> estack;
inline void tarjan(int x) {
  dfn[x] = low[x] = ++timer;
  vstack.push(x);
  for (int i = h[x]; i != 0; i = data[i].next) {
    int y = data[i].to;
    if (used[i >> 1]) continue;
    used[i >> 1] = true;
    estack.push(i >> 1);
    if (!dfn[y]) {
      tarjan(y);
      low[x] = min(low[x], low[y]);
      if (low[y] < dfn[x]) continue;
      ++bcc;
      while (true) {
        int z = vstack.top();
        vstack.pop();
        sz[bcc]++;
        if (z == y) break;
      }
      sz[bcc]++;
      while (1) {
        int j = estack.top();
        estack.pop();
        a[bcc].push_back(j);
        if (j == (i >> 1)) break;
      }
      continue;
    }
    low[x] = min(low[x], dfn[y]);
  }
}
int main() {
  scanf("%d%d", &n, &m);
  for (int i = 1; i <= m; i++) {
    int x, y;
    scanf("%d%d", &x, &y);
    data[++num].to = y;
    data[num].next = h[x];
    h[x] = num;
    data[++num].to = x;
    data[num].next = h[y];
    h[y] = num;
  }
  for (int i = 1; i <= n; i++)
    if (!dfn[i]) tarjan(i), vstack.pop();
  for (int i = 1; i <= bcc; i++) {
    if (sz[i] != a[i].size()) continue;
    for (int j = 0; j < a[i].size(); j++) f[a[i][j]] = 1, ++ans;
  }
  printf("%d\n", ans);
  for (int i = 1; i <= m; i++)
    if (f[i]) printf("%d ", i);
  printf("\n");
  return 0;
}
