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;
struct Edge {
  int to, next;
} edge[100010 << 1];
int num, head[100010], dfn[100010], low[100010], top, Index, stk[100010 << 2],
    n, m, tot;
set<int> ans, node[100010], line[100010];
inline int read() {
  int s = 0, w = 1;
  char c = getchar();
  for (; !isdigit(c); c = getchar())
    if (c == '-') w = -1;
  for (; isdigit(c); c = getchar()) s = (s << 1) + (s << 3) + (c ^ 48);
  return s * w;
}
void addedge(int x, int y) { edge[++num] = (Edge){y, head[x]}, head[x] = num; }
void tarjan(int u, int pre) {
  dfn[u] = low[u] = ++Index;
  for (int i = head[u]; i; i = edge[i].next) {
    int v = edge[i].to;
    if (!dfn[v]) {
      stk[++top] = i >> 1, stk[++top] = u, stk[++top] = v;
      tarjan(v, u);
      low[u] = min(low[u], low[v]);
      if (low[v] >= dfn[u]) {
        ++tot;
        while (1) {
          int t1, t2;
          node[tot].insert(t1 = stk[top--]);
          node[tot].insert(t2 = stk[top--]);
          line[tot].insert(stk[top--]);
          if (t1 == v && t2 == u) break;
        }
      }
    } else if (dfn[v] < dfn[u] && v != pre) {
      low[u] = min(low[u], dfn[v]);
      stk[++top] = i >> 1, stk[++top] = u, stk[++top] = v;
    }
  }
}
int main() {
  n = read(), m = read();
  for (int i = 1; i <= m; ++i) {
    int x = read(), y = read();
    addedge(x, y), addedge(y, x);
  }
  for (int i = 1; i <= n; ++i)
    if (!dfn[i]) tarjan(i, 0);
  for (int i = 1; i <= tot; ++i)
    if (node[i].size() == line[i].size())
      ans.insert(line[i].begin(), line[i].end());
  printf("%d\n", (int)ans.size());
  for (int i : ans) printf("%d ", i);
  return 0;
}
