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<vector<tuple<int, int, int>>> edges;
vector<int> order;
vector<tuple<int, int, int>> stack;
vector<vector<tuple<int, int, int>>> bcc;
int t;
int dfs(int root, int from = -1) {
  int ancient = order[root] = t++;
  for (auto x : edges[root]) {
    int to = get<2>(x);
    if (to != from) {
      if (order[to] == -1) {
        stack.push_back(x);
        int back = dfs(get<2>(x), root);
        if (back >= order[root]) {
          bcc.push_back({});
          do {
            bcc.back().push_back(stack.back());
            stack.pop_back();
          } while (bcc.back().back() != x);
        }
        ancient = min(ancient, back);
      } else if (order[to] < root) {
        stack.push_back(x);
        ancient = order[to];
      }
    }
  }
  return ancient;
}
int main() {
  int n, m;
  scanf("%d %d", &n, &m);
  edges = vector<vector<tuple<int, int, int>>>(n);
  for (int i = 0; i < m; ++i) {
    int from, to;
    scanf("%d %d", &from, &to);
    --from, --to;
    edges[from].push_back(make_tuple(i + 1, from, to));
    edges[to].push_back(make_tuple(i + 1, to, from));
  }
  order = vector<int>(n, -1);
  t = 0;
  for (int i = 0; i < n; ++i) {
    if (order[i] == -1) {
      dfs(i);
    }
  }
  vector<int> ans;
  for (auto b : bcc) {
    set<int> vertex;
    for (auto x : b) {
      vertex.insert(get<1>(x));
      vertex.insert(get<2>(x));
    }
    if (vertex.size() == b.size()) {
      for (auto x : b) {
        ans.push_back(get<0>(x));
      }
    }
  }
  sort(ans.begin(), ans.end());
  printf("%lu\n", ans.size());
  for (int i : ans) {
    printf("%d ", i);
  }
  printf("\n");
  return 0;
}
