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 = int(1e5 + 5);
int n, m;
int s, t, ncnt;
struct edge {
  int to, id;
  edge(){};
  edge(int T, int I) {
    to = T;
    id = I;
  }
};
stack<int> S;
vector<edge> G[MAXN];
set<int> Ans;
bool vis[MAXN];
int dfn[MAXN], low[MAXN];
void Addedge(int u, int v, int id) {
  G[u].push_back(edge(v, id));
  G[v].push_back(edge(u, id));
}
void Dfs(int u, int fa) {
  S.push(u);
  low[u] = dfn[u] = ++ncnt;
  for (int i = 0; i < G[u].size(); i++) {
    int v = G[u][i].to, id = G[u][i].id;
    if (!dfn[v]) {
      Dfs(v, u);
      low[u] = min(low[u], low[v]);
      if (low[v] >= dfn[u]) {
        set<int> tmp1;
        vector<int> tmp2;
        int t;
        do {
          t = S.top();
          S.pop();
          vis[t] = 1;
          tmp2.push_back(t);
        } while (t != u);
        S.push(u);
        for (int j = 0; j < tmp2.size(); j++) {
          int v = tmp2[j];
          for (int k = 0; k < G[v].size(); k++)
            if (vis[G[v][k].to]) tmp1.insert(G[v][k].id);
        }
        if (tmp1.size() == tmp2.size()) Ans.insert(tmp1.begin(), tmp1.end());
        for (int j = 0; j < tmp2.size(); j++) vis[tmp2[j]] = 0;
      }
    } else if (v != fa)
      low[u] = min(low[u], dfn[v]);
  }
}
int main() {
  scanf("%d%d", &n, &m);
  for (int i = 1; i <= m; i++) {
    int u, v;
    scanf("%d%d", &u, &v);
    Addedge(u, v, i);
  }
  for (int i = 1; i <= n; i++)
    if (!dfn[i]) Dfs(i, -1);
  printf("%d\n", Ans.size());
  for (auto i : Ans) printf("%d ", i);
}
