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 = 1e6 + 10, M = 2e6 + 10;
int head[N], ver[M], nxt[M], tot = 1;
void add(int x, int y) {
  ver[++tot] = y;
  nxt[tot] = head[x];
  head[x] = tot;
}
int st[N], low[N], cnt = 0, num = 0, dfn[N], rt, top, st1[N], top1;
bool cut[N];
vector<int> dcc[N];
int col[N];
int c[N];
set<int> v[N], e[N];
void tarjan(int x, int fa) {
  dfn[x] = low[x] = ++num;
  int c = 0;
  for (int i = head[x]; i; i = nxt[i]) {
    int y = ver[i];
    if (!dfn[y]) {
      st[++top] = x;
      st[++top] = y;
      st[++top] = i / 2;
      tarjan(y, x);
      low[x] = min(low[x], low[y]);
      if (low[y] >= dfn[x]) {
        c++;
        if (x != rt || c > 1) cut[x] = 1;
        cnt++;
        while (1) {
          int pos = st[top--], V = st[top--], U = st[top--];
          v[cnt].insert(U);
          v[cnt].insert(V);
          e[cnt].insert(pos);
          if (x == U && V == y) break;
        }
      }
    } else if (dfn[y] < dfn[x] && y != fa) {
      low[x] = min(low[x], dfn[y]);
      st[++top] = x;
      st[++top] = y;
      st[++top] = i / 2;
    }
  }
}
int main() {
  int n, m;
  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);
  }
  for (int i = 1; i <= n; i++)
    if (!dfn[i]) {
      rt = i;
      tarjan(i, 0);
    }
  int ans = 0;
  set<int> Ans;
  for (int i = 1; i <= cnt; i++)
    if (e[i].size() == v[i].size())
      for (set<int>::iterator it = e[i].begin(); it != e[i].end(); it++)
        Ans.insert(*it);
  printf("%d\n", (int)Ans.size());
  for (set<int>::iterator it = Ans.begin(); it != Ans.end(); it++)
    printf("%d ", *it);
  return 0;
}
