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 Arc {
  int v, i;
};
const int N = 1e5;
const int M = 1e5;
int n, m;
struct {
  int u, v;
} edge[M];
vector<Arc> vs[N];
int visited[N];
int depth[N];
int ascent[N];
bool bridge[M];
int bcc[N];
int nbNodes[N];
int nbEdges[N];
int dfs(int u, int p, int d) {
  if (visited[u] == 1)
    return depth[u];
  else if (visited[u] == 0) {
    visited[u] = 1;
    depth[u] = ascent[u] = d;
    for (Arc a : vs[u])
      if (a.v != p) {
        int r = dfs(a.v, u, d + 1);
        if (r <= d) bridge[a.i] = false;
        ascent[u] = min(ascent[u], r);
      }
  }
  return ascent[u];
}
void fillBcc(int u, int c) {
  if (bcc[u] == -1) {
    bcc[u] = c;
    for (Arc a : vs[u])
      if (!bridge[a.i]) fillBcc(a.v, c);
  }
}
int main() {
  scanf("%d%d", &n, &m);
  for (int i = 0; i < m; i++) {
    int u, v;
    scanf("%d%d", &u, &v);
    u--, v--;
    edge[i] = {u, v};
    vs[u].push_back({v, i});
    vs[v].push_back({u, i});
  }
  fill(bridge, bridge + m, true);
  for (int u = 0; u < n; u++) dfs(u, -1, 0);
  int nbBccs = 0;
  fill(bcc, bcc + n, -1);
  for (int u = 0; u < n; u++)
    if (bcc[u] == -1) fillBcc(u, nbBccs++);
  for (int u = 0; u < n; u++) nbNodes[bcc[u]]++;
  for (int i = 0; i < m; i++) {
    int u = edge[i].u, v = edge[i].v;
    int c = bcc[u];
    nbEdges[c] += bcc[u] == bcc[v];
  }
  vector<int> simple;
  for (int i = 0; i < m; i++) {
    int u = edge[i].u, v = edge[i].v;
    int c = bcc[u];
    if (bcc[u] == bcc[v] && nbEdges[c] == nbNodes[c]) simple.push_back(i);
  }
  printf("%ld\n", simple.size());
  for (int i : simple) printf("%d ", i + 1);
}
