#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 1;
const int M = N << 1 | 1;
char O[1 << 14], *S = O, *T = O;
inline int read() {
  int x = 0, f = 1;
  char ch =
      (S == T && (T = (S = O) + fread(O, 1, 1 << 14, stdin), S == T) ? -1
                                                                     : *S++);
  while (ch < '0' || ch > '9') {
    if (ch == '-') f = -1;
    ch = (S == T && (T = (S = O) + fread(O, 1, 1 << 14, stdin), S == T) ? -1
                                                                        : *S++);
  }
  while (ch >= '0' && ch <= '9') {
    x = (x << 1) + (x << 3) + (ch ^ 48);
    ch = (S == T && (T = (S = O) + fread(O, 1, 1 << 14, stdin), S == T) ? -1
                                                                        : *S++);
  }
  return x * f;
}
struct edge {
  int y, nxt;
} e[M];
int li[N];
inline void add(int u, int v) {
  static int top = 0;
  e[++top] = (edge){v, li[u]};
  li[u] = top;
  e[++top] = (edge){u, li[v]};
  li[v] = top;
}
int dfn[N], low[N], clk, bccno[N], bcccnt, top, stk[M];
int ck[M], ans[M], ckt, anst;
void dfs(int u, int fa) {
  dfn[u] = low[u] = ++clk;
  for (int t = li[u]; t; t = e[t].nxt) {
    int v = e[t].y;
    if (v == fa) continue;
    if (!dfn[v]) {
      stk[top++] = t;
      dfs(v, u);
      low[u] = min(low[v], low[u]);
      if (low[v] >= dfn[u]) {
        bcccnt++;
        bool ok = 1;
        ckt = 0;
        while (1) {
          int x = stk[--top];
          ck[ckt++] = ((x + 1) >> 1);
          if (bccno[e[x].y] != bcccnt)
            bccno[e[x].y] = bcccnt;
          else
            ok = 0;
          if (x == t) break;
        }
        if (ok && ckt > 1)
          for (int i = 0; i < ckt; ++i) ans[anst++] = ck[i];
      }
    } else if (dfn[v] < dfn[u]) {
      low[u] = min(dfn[v], low[u]);
      stk[top++] = t;
    }
  }
}
int main() {
  int n = read(), m = read();
  for (int i = 0; i < m; ++i) {
    int u = read(), v = read();
    add(u, v);
  }
  for (int i = 1; i <= n; ++i)
    if (!dfn[i]) dfs(i, -1);
  sort(ans, ans + anst);
  printf("%d\n", anst);
  for (int i = 0; i < anst; ++i) printf("%d ", ans[i]);
  return 0 * putchar(10);
}
