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 + 10;
int n, m, tot, top, h[maxn], tin[maxn], low[maxn], st[maxn * 3], now = 0,
                                                                 cnt = 1;
struct edges {
  int nxt, to;
} e[maxn << 1];
set<int> ans, edge[maxn], node[maxn];
void addline(int u, int v) { e[++cnt] = edges{h[u], v}, h[u] = cnt; }
void tarjan(int u, int f) {
  tin[u] = low[u] = ++now;
  for (int i = h[u]; i; i = e[i].nxt) {
    int v = e[i].to;
    if (!tin[v]) {
      st[++top] = i >> 1, st[++top] = u, st[++top] = v;
      tarjan(v, u);
      low[u] = min(low[u], low[v]);
      if (tin[u] <= low[v]) {
        tot++;
        while (1) {
          int t1, t2;
          node[tot].insert(t1 = st[top--]);
          node[tot].insert(t2 = st[top--]);
          edge[tot].insert(st[top--]);
          if (t1 == v && t2 == u) break;
        }
      }
    } else if (tin[v] < tin[u] && v != f) {
      st[++top] = i >> 1, st[++top] = u, st[++top] = v;
      low[u] = min(low[u], tin[v]);
    }
  }
}
int main() {
  scanf("%d%d", &n, &m);
  for (int i = 1; i <= m; i++) {
    int u, v;
    scanf("%d%d", &u, &v);
    addline(u, v), addline(v, u);
  }
  for (int i = 1; i <= n; i++) {
    if (!tin[i]) tarjan(i, 0);
  }
  for (int i = 1; i <= tot; i++) {
    if (edge[i].size() == node[i].size()) {
      ans.insert(edge[i].begin(), edge[i].end());
    }
  }
  printf("%d\n", (int)ans.size());
  for (int u : ans) printf("%d ", u);
  return 0;
}
