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;
vector<int> Ver[100100];
vector<int> id[100100];
int n, m;
vector<int> bcc[100100];
int bcccnt, low[100100], dfn[100100], dfn_cnt, stk[100100], top;
set<int> bccid[100100];
inline void tarjan(int x, int lst) {
  low[x] = dfn[x] = ++dfn_cnt;
  for (int i = 0; i < (int)Ver[x].size(); i++) {
    int y = Ver[x][i];
    if (y == lst) continue;
    if (!dfn[y]) {
      stk[++top] = y;
      tarjan(y, x);
      if (low[y] >= dfn[x]) {
        bcccnt++;
        do {
          bcc[bcccnt].push_back(stk[top]);
          bccid[stk[top]].insert(bcccnt);
        } while (stk[top--] != y);
        bcc[bcccnt].push_back(x);
        bccid[x].insert(bcccnt);
      }
      low[x] = min(low[x], low[y]);
    }
    low[x] = min(low[x], dfn[y]);
  }
}
int u[100100], v[100100];
inline void init() {
  scanf("%d%d", &n, &m);
  for (int i = 1; i <= m; i++) {
    scanf("%d%d", u + i, v + i);
    Ver[u[i]].push_back(v[i]), Ver[v[i]].push_back(u[i]);
    id[u[i]].push_back(i);
    id[v[i]].push_back(i);
  }
  for (int i = 1; i <= n; i++)
    if (!dfn[i]) tarjan(i, 0);
}
set<int> ans;
inline void solve(int p) {
  int cnt = 0;
  for (int i = 0; i < (int)bcc[p].size(); i++) {
    int x = bcc[p][i];
    if (Ver[x].size() > 50000) continue;
    for (int j = 0; j < (int)Ver[x].size(); j++) {
      int y = Ver[x][j];
      if (bccid[y].count(p)) cnt++;
    }
  }
  cnt /= 2;
  if (cnt == (int)bcc[p].size()) {
    for (int i = 0; i < (int)bcc[p].size(); i++) {
      int x = bcc[p][i];
      if (Ver[x].size() > 50000) continue;
      for (int j = 0; j < (int)Ver[x].size(); j++) {
        int y = Ver[x][j];
        if (bccid[y].count(p)) ans.insert(id[x][j]);
      }
    }
  }
}
int main() {
  init();
  for (int i = 1; i <= bcccnt; i++) solve(i);
  cout << ans.size() << endl;
  for (set<int>::iterator it = ans.begin(); it != ans.end(); it++)
    printf("%d ", *it);
}
