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 = 102000;
int n, m;
struct edge {
  int from, to;
} e[maxn];
vector<pair<int, int> > g[maxn];
int dfn[maxn], f[maxn], dd[maxn], cl, pt[maxn];
int chs[maxn], lnk[maxn];
void read() {
  scanf("%d%d", &n, &m);
  for (int i = 1; i <= m; i++) {
    scanf("%d%d", &e[i].from, &e[i].to);
    g[e[i].from].push_back(make_pair(e[i].to, i));
    g[e[i].to].push_back(make_pair(e[i].from, i));
  }
}
vector<int> ans;
vector<int> t[maxn];
void dfs(int now, int fa) {
  dfn[now] = ++cl;
  pt[now] = fa;
  for (int i = 0; i < g[now].size(); i++) {
    pair<int, int> pr = g[now][i];
    if (pr.first == fa) continue;
    if (!dfn[pr.first]) {
      t[now].push_back(pr.first);
      chs[pr.second] = 1;
      lnk[pr.first] = pr.second;
      dfs(pr.first, now);
    } else {
      if (dfn[pr.first] > dfn[now]) continue;
      f[now]++;
      f[pr.first]--;
    }
  }
}
int im[maxn];
void dfs2(int now) {
  for (int i = 0; i < t[now].size(); i++) {
    dfs2(t[now][i]);
    dd[now] += dd[t[now][i]];
  }
  dd[now] += f[now];
}
void dfs3(int now) {
  im[now] = im[pt[now]] + (dd[now] > 1);
  for (int i = 0; i < t[now].size(); i++) {
    dfs3(t[now][i]);
  }
}
void solve(int now) {
  if (dfn[e[now].from] < dfn[e[now].to]) swap(e[now].from, e[now].to);
  int kk = im[e[now].from] - im[e[now].to];
  if (kk == 0) {
    int pla = e[now].from;
    while (pla != e[now].to) {
      ans.push_back(lnk[pla]);
      pla = pt[pla];
    }
    ans.push_back(now);
  }
}
void work() {
  for (int i = 1; i <= n; i++) {
    if (!dfn[i]) dfs(i, 0), dfs2(i), dfs3(i);
  }
  for (int i = 1; i <= m; i++) {
    if (!chs[i]) solve(i);
  }
  sort(ans.begin(), ans.end());
  printf("%d\n", ans.size());
  for (int i = 0; i < ans.size(); i++) {
    printf("%d ", ans[i]);
  }
}
int main() {
  read();
  work();
  return 0;
}
