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;
int depth[500500];
vector<int> G[500500];
int color[500500];
int Ans;
int low[500500];
int X[500500], Y[500500];
int haveEdge[500500], haveVert[500500];
void dfs(int x, int last) {
  color[x] = 1;
  if (last != -1) depth[x] = depth[last] + 1;
  low[x] = depth[x];
  for (int i = 0; i < (G[x].size()); i++)
    if (G[x][i] != last)
      if (color[G[x][i]] == 0) {
        dfs(G[x][i], x);
        low[x] = min(low[x], low[G[x][i]]);
      } else
        low[x] = min(low[x], depth[G[x][i]]);
  haveVert[low[x]]++;
  color[x] = 2;
}
int main() {
  int N, K;
  cin >> N >> K;
  for (int i = 0; i < K; i++) {
    cin >> X[i] >> Y[i];
    X[i]--;
    Y[i]--;
    G[X[i]].push_back(Y[i]);
    G[Y[i]].push_back(X[i]);
  }
  for (int i = 0; i < N; i++)
    if (color[i] == 0) dfs(i, -1);
  for (int i = 0; i < K; i++)
    if (low[X[i]] == low[Y[i]]) haveEdge[low[X[i]]]++;
  for (int i = 0; i < K; i++)
    if (low[X[i]] == low[Y[i]] && haveVert[low[X[i]]] == haveEdge[low[X[i]]])
      Ans++;
  cout << Ans << endl;
  for (int i = 0; i < K; i++)
    if (low[X[i]] == low[Y[i]] && haveVert[low[X[i]]] == haveEdge[low[X[i]]])
      cout << i + 1 << " ";
  return 0;
}
