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 N = 1234567;
inline int read() {
  int p = 0;
  int f = 1;
  char ch = getchar();
  while (ch < '0' || ch > '9') {
    if (ch == '-') f = -1;
    ch = getchar();
  }
  while (ch >= '0' && ch <= '9') {
    p = p * 10 + ch - '0';
    ch = getchar();
  }
  return p * f;
}
struct node {
  int x, y, next;
} edge[N];
int len, first[N];
void ins(int x, int y) {
  len++;
  edge[len].x = x;
  edge[len].y = y;
  edge[len].next = first[x];
  first[x] = len;
}
int dfn[N], low[N], id = 0, cnt = 0;
stack<int> s;
int n, m;
vector<int> scc[N];
int bel[N];
void dfs(int x) {
  dfn[x] = low[x] = ++id;
  s.push(x);
  for (int k = first[x]; k != -1; k = edge[k].next) {
    int y = edge[k].y;
    if (dfn[y] == -1) {
      dfs(y);
      low[x] = min(low[x], low[y]);
      if (low[y] >= dfn[x]) {
        cnt++;
        scc[cnt].push_back(x);
        int i;
        do {
          i = s.top();
          scc[cnt].push_back(i);
          bel[i] = cnt;
          s.pop();
        } while (i != y);
      }
    } else
      low[x] = min(low[x], dfn[y]);
  }
}
vector<int> siz[N];
vector<int> v;
int main() {
  len = 1;
  memset(first, -1, sizeof(first));
  n = read();
  m = read();
  for (int i = 1; i <= m; i++) {
    int x = read();
    int y = read();
    ins(x, y);
    ins(y, x);
  }
  memset(dfn, -1, sizeof(dfn));
  memset(low, -1, sizeof(low));
  cnt = 0;
  for (int i = 1; i <= n; i++)
    if (dfn[i] == -1) {
      while (!s.empty()) s.pop();
      dfs(i);
    }
  for (int i = 2; i <= len; i += 2) {
    int p = dfn[edge[i].x] > dfn[edge[i].y] ? edge[i].x : edge[i].y;
    siz[bel[p]].push_back(i / 2);
  }
  for (int i = 1; i <= cnt; i++) {
    if (scc[i].size() == siz[i].size())
      for (auto j : siz[i]) v.push_back(j);
  }
  printf("%d\n", v.size());
  sort(v.begin(), v.end());
  for (int i = 0; i < v.size(); i++)
    printf("%d%c", v[i], " \n"[i == v.size() - 1]);
  return 0;
}
