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 = 100005;
const int maxm = 100005;
struct E {
  int v, nxt, id;
} edge[maxn * 2];
int head[maxn], tot;
void init() {
  memset(head, -1, sizeof(head));
  tot = 0;
}
void addedge(int u, int v, int id) {
  edge[tot].v = v;
  edge[tot].id = id;
  edge[tot].nxt = head[u];
  head[u] = tot++;
  edge[tot].v = u;
  edge[tot].id = id;
  edge[tot].nxt = head[v];
  head[v] = tot++;
}
int low[maxn], dfn[maxn], Index;
int sta[maxn], top;
int sta2[maxn], top2;
int n, m;
int ans[maxn], num;
void tarjan(int u, int pre) {
  low[u] = dfn[u] = ++Index;
  sta[top++] = u;
  for (int i = head[u]; i != -1; i = edge[i].nxt) {
    int v = edge[i].v;
    if (v == pre) continue;
    if (!dfn[v]) {
      int pos = top2;
      sta2[top2++] = edge[i].id;
      tarjan(v, u);
      low[u] = min(low[u], low[v]);
      if (dfn[u] <= low[v]) {
        int sz = 1;
        while (sta[top - 1] != u) {
          sz++, top--;
        }
        if (top2 - pos == sz) {
          num += sz;
          while (top2 > pos) ans[sta2[--top2]] = 1;
        }
        top2 = pos;
      }
    } else if (dfn[u] > dfn[v]) {
      low[u] = min(low[u], dfn[v]);
      sta2[top2++] = edge[i].id;
    }
  }
}
void solve() {
  memset(dfn, 0, sizeof(dfn));
  top = top2 = Index = 0;
  for (int i = 1; i <= n; i++) {
    if (!dfn[i]) tarjan(i, i);
    top = 0;
  }
}
int main() {
  ios::sync_with_stdio(false);
  init();
  cin >> n >> m;
  for (int i = 1; i <= m; i++) {
    int u, v;
    cin >> u >> v;
    addedge(u, v, i);
  }
  solve();
  cout << num << endl;
  for (int i = 1; i <= m; i++) {
    if (ans[i]) cout << i << " ";
  }
  return 0;
}
