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 N = 100010;
int k, n, m, x, y;
int low[N], dfn[N], tc;
int st[N], top;
int h[N], t[N << 1], nx[N << 1], num = 1;
int vis[N], cur;
bool b[N << 1];
int a[N], A[N], ncnt;
void Add(int x, int y) {
  t[++num] = y;
  nx[num] = h[x];
  h[x] = num;
}
void Dfs(int x, int y) {
  dfn[x] = low[x] = ++tc;
  for (int i = h[x]; i; i = nx[i])
    if (t[i] != y && !b[i]) {
      b[i] = b[i ^ 1] = 1;
      st[++top] = i;
      int v = t[i];
      if (!dfn[v]) {
        Dfs(v, x);
        low[x] = min(low[x], low[v]);
        if (dfn[x] <= low[v]) {
          int cnt = 0, Top = 0;
          ++cur;
          while (st[top] != i) {
            int x = st[top--];
            if (vis[t[x]] != cur) vis[t[x]] = cur, ++cnt;
            if (vis[t[x ^ 1]] != cur) vis[t[x ^ 1]] = cur, ++cnt;
            a[++Top] = x;
          }
          if (vis[t[i]] != cur) vis[t[i]] = cur, ++cnt;
          if (vis[t[i ^ 1]] != cur) vis[t[i ^ 1]] = cur, ++cnt;
          a[++Top] = i;
          --top;
          if (dfn[x] == low[v] && cnt == Top) {
            for (int i = 1; i <= Top; i++) A[++ncnt] = a[i];
          }
        }
      } else
        low[x] = min(low[x], dfn[v]);
    }
}
int main() {
  scanf("%d%d", &n, &m);
  for (int i = 1; i <= m; i++) scanf("%d%d", &x, &y), Add(x, y), Add(y, x);
  for (int i = 1; i <= n; i++)
    if (!dfn[i]) Dfs(i, 0);
  cout << ncnt << endl;
  sort(A + 1, A + ncnt + 1);
  for (int i = 1; i <= ncnt; i++) printf("%d ", A[i] >> 1);
  return 0;
}
