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 = 100010;
const int maxm = 200010;
int head[maxn], cnt;
void init(int n) {
  for (int i = 1; i <= n; i++) head[i] = -1;
  cnt = 0;
}
struct edge {
  int to, next;
} E[maxm];
void add(int u, int v) {
  E[cnt].to = v;
  E[cnt].next = head[u];
  head[u] = cnt++;
}
int low[maxn], dfn[maxn], stk[maxn], idx, top, block;
int inbcc[maxn], bl[maxn], ect[maxn], vis[maxn], num[maxn];
vector<int> bcc[maxn];
vector<int> ebcc[maxn];
void tarjan(int u, int pre) {
  low[u] = dfn[u] = ++idx;
  stk[++top] = u;
  for (int i = head[u]; ~i; i = E[i].next) {
    int v = E[i].to;
    if (v == pre) continue;
    if (!dfn[v]) {
      tarjan(v, u);
      low[u] = min(low[u], low[v]);
      if (low[v] >= dfn[u]) {
        block++;
        bcc[block].clear();
        int vv;
        do {
          vv = stk[top--];
          bl[vv] = block;
          bcc[block].push_back(vv);
          inbcc[vv]++;
        } while (vv != v);
        bcc[block].push_back(u);
        inbcc[u]++;
        bl[u] = block;
      }
    } else {
      low[u] = min(low[u], dfn[v]);
    }
  }
}
int main() {
  int n, m;
  scanf("%d%d", &n, &m);
  init(n);
  for (int i = 1; i <= m; i++) {
    int u, v;
    scanf("%d%d", &u, &v);
    add(u, v);
    add(v, u);
  }
  for (int i = 1; i <= n; i++) {
    if (!dfn[i]) tarjan(i, -1);
  }
  for (int i = 0; i < cnt; i += 2) {
    int u = E[i].to, v = E[i ^ 1].to;
    if (inbcc[u] > 1 && inbcc[v] > 1) continue;
    if (inbcc[u] > 1) {
      num[bl[v]]++;
      ebcc[bl[v]].push_back(i >> 1);
    } else {
      num[bl[u]]++;
      ebcc[bl[u]].push_back(i >> 1);
    }
  }
  int ans = 0;
  vector<int> ansp;
  for (int i = 1; i <= block; i++) {
    if (num[i] == (int)bcc[i].size()) {
      ans += num[i];
      for (int j : ebcc[i]) {
        ansp.push_back(j);
      }
    }
  }
  sort(ansp.begin(), ansp.end());
  printf("%d\n", ans);
  for (int x : ansp) {
    printf("%d ", x + 1);
  }
  puts("");
  return 0;
}
