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 edge {
  int to, nxt;
};
int head[100010], cnt;
int ans;
edge e[200010];
int dfn[100010], low[100010], ind;
int stk[200010], top;
int col[100010], num;
int deg[100010];
bool ok[100010];
int n, m;
void addedge(int a, int b) {
  e[cnt].to = b;
  e[cnt].nxt = head[a];
  head[a] = cnt++;
  deg[a]++;
}
void tarjan(int x, int p) {
  dfn[x] = low[x] = ++ind;
  for (int i = head[x]; i != -1; i = e[i].nxt) {
    int y = e[i].to;
    if (y == p) continue;
    stk[++top] = i;
    if (!dfn[y]) {
      tarjan(y, x);
      low[x] = min(low[x], low[y]);
      if (low[y] >= dfn[x]) {
        num++;
        int nod = 0, edg = 0;
        vector<int> es;
        while (top && stk[top] != i) {
          int p = e[stk[top]].to;
          if (col[p] != num) col[p] = num, nod++;
          edg++;
          es.push_back(stk[top]);
          top--;
        }
        int p = e[stk[top]].to;
        if (col[p] != num) col[p] = num, nod++;
        edg++;
        es.push_back(stk[top]);
        top--;
        if (col[x] != num) col[x] = num, nod++;
        if (nod == edg) {
          ans += edg;
          for (int j = 0; j < (int)es.size(); j++) ok[es[j] / 2 + 1] = true;
        }
      }
    }
    low[x] = min(low[x], dfn[y]);
  }
}
int main() {
  scanf("%d%d", &n, &m);
  for (int i = 1; i <= n; i++) head[i] = -1;
  for (int i = 1; i <= m; i++) {
    int a, b;
    scanf("%d%d", &a, &b);
    addedge(a, b);
    addedge(b, a);
  }
  for (int i = 1; i <= n; i++) {
    if (dfn[i]) continue;
    tarjan(i, 0);
  }
  printf("%d\n", ans);
  for (int i = 1; i <= m; i++)
    if (ok[i]) printf("%d ", i);
  return 0;
}
