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 MAX = 100;
int U[MAX], V[MAX];
vector<int> ed[MAX];
bool cut[MAX];
int tot, Time, low[MAX], st[MAX];
vector<int> bccV[MAX], bccE[MAX];
stack<int> S;
void popBCC(int e) {
  ++tot;
  while (S.top() != e) bccE[tot].push_back(S.top()), S.pop();
  bccE[tot].push_back(S.top()), S.pop();
}
void dfs(int s, int p = -1) {
  int ch = 0;
  st[s] = low[s] = ++Time;
  for (int e : ed[s]) {
    int x = s ^ U[e] ^ V[e];
    if (!st[x]) {
      ch++;
      S.push(e);
      dfs(x, s);
      low[s] = min(low[s], low[x]);
      if (p != -1 and low[x] >= st[s])
        cut[s] = 1, popBCC(e);
      else if (p == -1)
        if (ch > 1) cut[s] = 1, popBCC(e);
    } else if (p != x and st[x] < low[s])
      low[s] = st[x], S.push(e);
  }
  if (p == -1 && ch > 1) cut[s] = 1;
}
void processBCC(int n) {
  for (int i = 1; i <= n; i++) bccV[i].clear(), bccE[i].clear();
  memset(st, 0, sizeof(st));
  memset(cut, 0, sizeof(cut));
  Time = tot = 0;
  for (int i = 1; i <= n; i++) {
    if (!st[i]) {
      dfs(i, -1);
      if (!S.empty()) ++tot;
      while (!S.empty()) bccE[tot].push_back(S.top()), S.pop();
    }
  }
  for (int i = 1; i <= tot; i++) {
    for (int e : bccE[i]) {
      bccV[i].push_back(U[e]);
      bccV[i].push_back(V[e]);
    }
  }
  for (int i = 1; i <= tot; i++) {
    sort(bccV[i].begin(), bccV[i].end());
    bccV[i].erase(unique(bccV[i].begin(), bccV[i].end()), bccV[i].end());
  }
}
int main() {
  int n, m;
  scanf("%d %d", &n, &m);
  for (int i = 1; i <= m; i++) {
    scanf("%d %d", &U[i], &V[i]);
    ed[U[i]].push_back(i);
    ed[V[i]].push_back(i);
  }
  processBCC(n);
  vector<int> ans;
  for (int i = 1; i <= tot; i++) {
    if (bccV[i].size() == bccE[i].size())
      for (int e : bccE[i]) ans.push_back(e);
  }
  sort(ans.begin(), ans.end());
  printf("%d\n", ans.size());
  for (int v : ans) printf("%d ", v);
  puts("");
  return 0;
}
