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 MAXN = 2e5 + 5;
int head[MAXN], tot;
int DFN[MAXN], LOW[MAXN], cut[MAXN];
int bcc_num, bel_bcc[MAXN], bcc[MAXN], cnt;
struct node {
  int to, next, id;
} e[MAXN * 3];
struct edge {
  int x, y;
};
stack<pair<edge, int> > s;
vector<int> ans[MAXN];
void add(int x, int y, int id) {
  e[tot].next = head[x];
  e[tot].to = y;
  e[tot].id = id;
  head[x] = tot++;
}
void tarjan(int u, int fa) {
  DFN[u] = LOW[u] = ++cnt;
  int child = 0;
  for (int i = head[u]; i != -1; i = e[i].next) {
    int temp = e[i].to;
    edge E;
    E.x = u, E.y = temp;
    if (!DFN[temp]) {
      s.push(make_pair(E, e[i].id));
      child++;
      tarjan(temp, u);
      LOW[u] = min(LOW[u], LOW[temp]);
      if (LOW[temp] >= DFN[u]) {
        cut[u] = 1;
        bcc_num++;
        edge t;
        int sum = 0;
        while (1) {
          t = s.top().first;
          int id = s.top().second;
          s.pop();
          if (bel_bcc[t.x] != bcc_num) sum++, bel_bcc[t.x] = bcc_num;
          if (bel_bcc[t.y] != bcc_num) sum++, bel_bcc[t.y] = bcc_num;
          ans[bcc_num].push_back(id);
          if (t.x == u && t.y == temp) break;
        }
        bcc[bcc_num] = sum;
      }
    } else if (DFN[temp] < DFN[u] && temp != fa) {
      s.push(make_pair(E, e[i].id));
      LOW[u] = min(LOW[u], DFN[temp]);
    }
  }
  if (fa == -1 && child == 1) cut[u] = 0;
}
int main() {
  int n, m;
  scanf("%d%d", &n, &m);
  memset(head, -1, sizeof(head));
  for (int i = 1; i <= m; i++) {
    int x, y;
    scanf("%d%d", &x, &y);
    add(x, y, i);
    add(y, x, i);
  }
  for (int i = 1; i <= n; i++) {
    if (!DFN[i]) tarjan(i, -1);
  }
  vector<int> o;
  for (int i = 1; i <= bcc_num; i++) {
    if (bcc[i] == ans[i].size()) {
      for (int j = 0; j < ans[i].size(); j++) o.push_back(ans[i][j]);
    }
  }
  sort(o.begin(), o.end());
  printf("%d\n", o.size());
  for (int i = 0; i < o.size(); i++)
    printf("%d%c", o[i], i == o.size() - 1 ? '\n' : ' ');
  return 0;
}
