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>
#define int long long
#define fo(i, n) for(int i = 1; i <= (n); i ++)
#define out(x) cerr << #x << " = " << x << "\n"
#define type(x) __typeof((x).begin())
#define foreach(it, x) for(type(x) it = (x).begin(); it != (x).end(); ++ i)
using namespace std;
// by piano
template<typename tp> inline void read(tp &x) {
  x = 0;char c = getchar(); bool f = 0;
  for(; c < '0' || c > '9'; f |= (c == '-'), c = getchar());
  for(; c >= '0' && c <= '9'; x = (x << 3) + (x << 1) + c - '0', c = getchar());
  if(f) x = -x;
}
template<typename tp> inline void arr(tp *a, int n) {
  for(int i = 1; i <= n; i ++)
    cout << a[i] << " ";
  puts("");
}
const int N = 3e5 + 233;
const int M = N;
struct E {
  int nxt, from, to, id;
}e[M << 1];
int head[N], e_cnt = 0, ban[N];
struct P {
  int first, second, id;
}S[N];
int top = 0;
int dfn[N], low[N], dfs_clock = 0, sccno[N], scc_cnt = 0;
int n, m;
set<int> points[N], edges[N];

inline void add(int u, int v, int id) {
  e[++ e_cnt] = (E) {head[u], u, v, id}; head[u] = e_cnt;
}

inline void tarjan(int u, int fat) {
  dfn[u] = low[u] = ++ dfs_clock;
  for(int i = head[u]; i; i = e[i].nxt) {
    int v = e[i].to;
    S[++ top] = {u, v, e[i].id};
    if(!dfn[v]) {
      tarjan(v, u);
      low[u] = min(low[u], low[v]);
      if(low[v] >= dfn[u]) {
        scc_cnt ++;
        for(;;) {
          auto it = S[top --];
          if(sccno[it.first] != scc_cnt) {
            sccno[it.first] = scc_cnt;
            points[scc_cnt].insert(it.first);
          }
          swap(it.first, it.second);
          if(sccno[it.first] != scc_cnt) {
            sccno[it.first] = scc_cnt;
            points[scc_cnt].insert(it.first);
          }
          edges[scc_cnt].insert(it.id);
          if(it.first == v && it.second == u)
            break;
        }
        // for(auto u: edges[scc_cnt]) cout << u << " "; puts("");
        // for(auto u: points[scc_cnt]) cout << u << " "; puts("");
      }
    }
    else
      low[u] = min(low[u], dfn[v]);
  }
}

main(void) {
  read(n); read(m);
  for(int i = 1; i <= m; i ++) {
    int u, v; read(u); read(v);
    add(u, v, i); add(v, u, i);
  }
  for(int i = 1; i <= n; i ++) if(!dfn[i]) tarjan(i, 0);
  set<int> ans;
  for(int i = 1; i <= scc_cnt; i ++) {
    set<int> &edges = ::edges[i], &points = ::points[i];
    if(edges.size() == points.size()) {
      for(auto e: edges)
        ans.insert(e);
    }
  }
  cout << ans.size() << "\n";
  for(auto e: ans) cout << e << " ";
  puts("");
}
