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 = 1e5 + 100;
int first[maxn], nxt[maxn * 2], from[maxn * 2], des[maxn * 2],
    isBrige[maxn * 2], tot;
int dfn[maxn], low[maxn], dfs_clock;
int cnt_e[maxn], cnt_n[maxn];
int bcc_cnt;
bool ok[maxn];
vector<int> ans;
int m, n;
inline void addEdge(int x, int y) {
  tot++;
  des[tot] = y;
  from[tot] = x;
  nxt[tot] = first[x];
  first[x] = tot;
}
void input() {
  cin >> n >> m;
  for (int i = 0; i < m; i++) {
    int u, v;
    scanf("%d%d", &u, &v);
    addEdge(u, v);
    addEdge(v, u);
  }
}
void dfs(int u, int fa) {
  dfn[u] = low[u] = ++dfs_clock;
  for (int t = first[u]; t; t = nxt[t]) {
    int v = des[t];
    if (v == fa) continue;
    if (!dfn[v]) {
      dfs(v, u);
      low[u] = min(low[v], low[u]);
      if (dfn[u] < low[v]) {
        isBrige[t] = true;
        if (t & 1) {
          isBrige[t + 1] = true;
        } else {
          isBrige[t - 1] = true;
        }
      }
    } else if (dfn[v] < dfn[u]) {
      low[u] = min(low[u], dfn[v]);
    }
  }
}
void blood_fill(int x) {
  dfn[x] = bcc_cnt;
  for (int t = first[x]; t; t = nxt[t]) {
    if (isBrige[t]) continue;
    int v = des[t];
    if (!dfn[v]) {
      blood_fill(v);
    }
  }
}
void check() {
  for (int i = 1; i <= n; i++) {
    cnt_n[dfn[i]]++;
  }
  for (int i = 1; i <= tot; i++) {
    if (isBrige[i]) continue;
    cnt_e[dfn[des[i]]]++;
  }
  for (int i = 1; i <= bcc_cnt; i++) {
    if (cnt_n[i] * 2 == cnt_e[i]) {
      ok[i] = 1;
    }
  }
}
void debug() {
  for (int i = 1; i <= tot; i++) {
    if (isBrige[i]) {
      cout << "Brige: " << i << endl;
    }
  }
}
void output() {
  for (int i = 1; i <= tot; i += 2) {
    if (isBrige[i]) continue;
    if (ok[dfn[des[i]]]) ans.push_back((i + 1) / 2);
  }
  sort(ans.begin(), ans.end());
  cout << ans.size() << endl;
  for (int i = 0; i < ans.size(); i++) {
    printf("%d ", ans[i]);
  }
}
void solve() {
  for (int i = 1; i <= n; i++) {
    if (!dfn[i]) dfs(i, -1);
  }
  memset(dfn, 0, sizeof dfn);
  for (int i = 1; i <= n; i++) {
    if (!dfn[i]) {
      bcc_cnt++;
      blood_fill(i);
    }
  }
  check();
  output();
}
int main() {
  input();
  solve();
  return 0;
}
