2 0
 100000 0
 8 9
1 2
2 3
3 4
4 1
5 6
6 7
7 8
8 5
6 8
 2 1
1 2
 11 9
5 9
8 5
11 3
11 1
3 4
7 11
3 1
11 2
7 2
 7 9
7 3
7 4
1 2
2 3
3 1
3 4
4 5
5 6
6 4
 7 5
5 4
7 3
7 1
6 7
3 1
 7 8
1 2
2 3
3 4
4 1
3 5
5 6
6 7
7 3
 6 9
1 2
2 3
1 4
4 2
5 2
5 3
4 5
6 4
6 5
 7 9
1 2
2 4
4 3
3 1
2 3
4 5
5 6
6 7
7 4
 1 0
 6 7
1 2
2 3
3 1
3 4
4 5
5 6
6 4
 4 5
1 2
2 3
3 4
4 1
1 3
 100000 3
99998 99999
99999 100000
100000 99998

0

 0

 4
1 2 3 4 
 0

 6
3 4 6 7 8 9 
 9
1 2 3 4 5 6 7 8 9 
 3
2 3 5 
 8
1 2 3 4 5 6 7 8 
 0

 4
6 7 8 9 
 0

 6
1 2 3 5 6 7 
 0

 3
1 2 3 

#include <bits/stdc++.h>
using namespace std;
const int N = 100005;
int n, m, cnt = 1, timer = 0, bcc = 0, ans = 0;
int h[N], dfn[N], low[N], sz[N];
bool f[N], vis[N];
struct edge {
  int to, nxt;
} e[N << 1];
vector<int> a[N];
stack<int> vst, est;
void add(int x, int y) {
  cnt++;
  e[cnt].to = y;
  e[cnt].nxt = h[x];
  h[x] = cnt;
}
void init() {
  scanf("%d%d", &n, &m);
  for (int i = 1; i <= m; i++) {
    int x, y;
    scanf("%d%d", &x, &y);
    add(x, y);
    add(y, x);
  }
}
void tarjan(int u) {
  dfn[u] = low[u] = ++timer;
  vst.push(u);
  for (int i = h[u]; i != 0; i = e[i].nxt) {
    int v = e[i].to;
    if (vis[i >> 1]) continue;
    vis[i >> 1] = 1;
    est.push(i >> 1);
    if (dfn[v] == 0) {
      tarjan(v);
      low[u] = min(low[u], low[v]);
      if (low[v] < dfn[u]) continue;
      ++bcc;
      while (1) {
        int mn = vst.top();
        vst.pop();
        sz[bcc]++;
        if (mn == v) break;
      }
      sz[bcc]++;
      while (1) {
        int mn = est.top();
        est.pop();
        a[bcc].push_back(mn);
        if (mn == i >> 1) break;
      }
      continue;
    }
    low[u] = min(low[u], dfn[v]);
  }
}
void work() {
  for (int i = 1; i <= n; i++) dfn[i] = 0;
  timer = 0;
  for (int i = 1; i <= n; i++) {
    if (!dfn[i]) tarjan(i), vst.pop();
  }
  for (int i = 1; i <= bcc; i++) {
    if (sz[i] != a[i].size()) continue;
    for (int j = 0; j < sz[i]; 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");
}
int main() {
  init();
  work();
  return 0;
}
