#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e5 + 10;
const int maxm = 2e6 + 10;
inline int read() {
  int x = 0, f = 1;
  char c = getchar();
  while (c > '9' || c < '0') {
    if (c == '-') f = -f;
    c = getchar();
  }
  while (c >= '0' && c <= '9') x = x * 10 + c - '0', c = getchar();
  return x * f;
}
int cnt, head[maxn], n, m;
struct edge {
  int v, next, id;
} edge[maxm << 1];
void add(int u, int v, int id) {
  edge[cnt].v = v;
  edge[cnt].id = id;
  edge[cnt].next = head[u];
  head[u] = cnt++;
}
set<int> ans;
pair<int, int> stk[maxm];
int low[maxn], dfn[maxn];
int top, tim, cntbrg, dccnum, rt, dsize[maxn], brg[maxn];
vector<int> dcc[maxn];
bool cut[maxn], vis[maxm << 1];
void init() {
  cntbrg = dccnum = tim = top = 0;
  for (int i = 1; i <= n; i++) {
    head[i] = -1;
    dfn[i] = low[i] = 0;
  }
}
void tarjan(int u, int pre) {
  dfn[u] = low[u] = ++tim;
  if (rt == u && head[u] == -1) {
    dcc[++dccnum].clear();
    dcc[dccnum].push_back(u);
    return;
  }
  int cntzs = 0;
  for (int i = head[u]; i != -1; i = edge[i].next) {
    int v = edge[i].v, id = edge[i].id;
    if (vis[id]) continue;
    vis[id] = 1;
    stk[++top] = make_pair(v, id);
    if (!dfn[v]) {
      tarjan(v, u);
      low[u] = min(low[u], low[v]);
      if (low[v] >= dfn[u]) {
        if (rt == u && cntzs > 1 || u != rt) cut[u] = 1;
        dcc[++dccnum].clear();
        pair<int, int> w;
        do {
          w = stk[top--];
          if (brg[w.first] != dccnum) {
            dsize[dccnum]++;
            brg[w.first] = dccnum;
          }
          dcc[dccnum].push_back(w.second);
        } while (w.second != id);
        if (dsize[dccnum] > 1 && dcc[dccnum].size() == dsize[dccnum]) {
          for (int j = 0; j < dsize[dccnum]; j++) ans.insert(dcc[dccnum][j]);
        }
      }
    } else if (v != pre)
      low[u] = min(low[u], dfn[v]);
  }
}
int main() {
  n = read(), m = read();
  init();
  for (int i = 1; i <= m; i++) {
    int u = read(), v = read();
    add(u, v, i);
    add(v, u, i);
  }
  for (int i = 1; i <= n; i++) {
    if (!dfn[i]) tarjan(i, i);
  }
  printf("%d\n", ans.size());
  for (auto it = ans.begin(); it != ans.end();) {
    printf("%d ", *it++);
  }
  puts("");
}
