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;
struct data {
  int to, head;
} e[50000];
stack<int> s;
int n, m, len = 1, len1, cnt, num;
int dfn[50000], low[50000], head[50000], la[50000], ans[50000], a[50000],
    vis[50000];
void add(int u, int v) {
  e[++len].to = v;
  e[len].head = head[u];
  head[u] = len;
}
void dfs(int lab, int fa) {
  dfn[lab] = low[lab] = ++cnt;
  for (int i = head[lab]; i; i = e[i].head) {
    if (e[i].to == fa) continue;
    if (!vis[i]) vis[i] = vis[i ^ 1] = 1, s.push(i);
    if (!dfn[e[i].to]) {
      dfs(e[i].to, lab);
      low[lab] = min(low[e[i].to], low[lab]);
      if (low[e[i].to] >= dfn[lab]) {
        num++;
        int m1, num1 = 0, len = 0;
        do {
          m1 = s.top();
          s.pop();
          if (la[e[m1].to] != num) la[e[m1].to] = num, num1++;
          if (la[e[m1 ^ 1].to] != num) la[e[m1 ^ 1].to] = num, num1++;
          a[++len] = m1 / 2;
        } while (m1 != i);
        if (num1 == len) {
          for (int i = 1; i <= len; i++) ans[++len1] = a[i];
        }
      }
    } else
      low[lab] = min(low[e[i].to], low[lab]);
  }
}
int main() {
  int u, v;
  scanf("%d%d", &n, &m);
  for (int i = 1; i <= m; i++) {
    scanf("%d%d", &u, &v);
    if (u > v) swap(u, v);
    add(u, v);
    add(v, u);
  }
  for (int i = 1; i <= n; i++) {
    if (!dfn[i]) dfs(i, 0);
  }
  sort(ans + 1, ans + len1 + 1);
  printf("%d\n", len1);
  for (int i = 1; i <= len1; i++) printf("%d ", ans[i]);
}
