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 mx = 2e5 + 5;
inline int read() {
  int X = 0;
  bool flag = 1;
  char ch = getchar();
  while (ch < '0' || ch > '9') {
    if (ch == '-') flag = 0;
    ch = getchar();
  }
  while (ch >= '0' && ch <= '9') {
    X = (X << 1) + (X << 3) + ch - '0';
    ch = getchar();
  }
  if (flag) return X;
  return ~(X - 1);
}
struct block {
  int u, v, idx;
};
int n, m;
int head[mx], nxt[mx], ver[mx], id[mx], tot = 1;
int low[mx], dfn[mx], num;
int bridge[mx], dep[mx];
int c[mx], c2[mx], cnt1[mx], cnt2[mx], cnt3[mx], vcc, ans[mx];
map<pair<int, int>, int> mp;
void add(int x, int y, int z) {
  ver[++tot] = y, id[tot] = z, nxt[tot] = head[x], head[x] = tot;
}
void tarjan(int x, int in_edge) {
  dfn[x] = low[x] = ++num;
  for (int i = head[x]; i; i = nxt[i]) {
    if (i == (in_edge ^ 1)) continue;
    int y = ver[i];
    if (!dfn[y]) {
      tarjan(y, i), low[x] = min(low[x], low[y]);
      if (low[y] > dfn[x]) {
        bridge[i] = bridge[i ^ 1] = 1;
      }
    } else
      low[x] = min(low[x], dfn[y]);
  }
}
void dfs(int x, int fath) {
  c[x] = vcc, cnt1[vcc]++;
  for (int i = head[x]; i; i = nxt[i]) {
    if (bridge[i] || ver[i] == fath) continue;
    int y = ver[i];
    if (mp[make_pair(x, y)] || mp[make_pair(y, x)]) continue;
    mp[make_pair(x, y)] = mp[make_pair(y, x)] = 1;
    c2[id[i]] = vcc, cnt2[vcc]++;
    if (!c[y]) dfs(y, x);
  }
}
int main() {
  n = read(), m = read();
  for (int i = 1; i <= m; i++) {
    int x = read(), y = read();
    add(x, y, i), add(y, x, i);
  }
  for (int i = 1; i <= n; i++)
    if (!dfn[i]) tarjan(i, 0);
  for (int i = 1; i <= n; i++)
    if (!c[i]) {
      vcc++, dfs(i, 0);
    }
  for (int i = 1; i <= vcc; i++)
    if (cnt1[i] == cnt2[i]) cnt3[i] = 1;
  int res = 0;
  for (int i = 1; i <= m; i++)
    if (cnt3[c2[i]]) res++;
  printf("%d\n", res);
  for (int i = 1; i <= m; i++)
    if (cnt3[c2[i]]) printf("%d ", i);
}
