#include <iostream>
#include <iomanip>
#include <cstdlib>
#include <algorithm>
#include <fstream>
#include <cstdio>
#include <cmath>
#include <cstring>
#include <string>
#include <ctime>
#include <queue>
#include <stack>
#include <vector>
#include <map>
#include <set>
#include <deque>

using namespace std;

#define fi first
#define se second
#define mp make_pair
#define sz(x) ((int)(x).size())
#define pb(x) push_back(x)
#define pf(x) push_front(x)
#define abs(x) ((x) < 0 ? -(x) : (x))
#define INF 2000000000
#define sqr(x) ((x) * (x))
#define all(x) x.begin(), x.end()
#define fname ""
#define MOD 1000000007
#define y1 google
#define tim printf("%.4lf\n", (clock() * 1.) / CLOCKS_PER_SEC)

int timer = 1, kol;

int tin[100500], fup[100500];
vector <int> a[200500],w[200500];
int ans[200500];
bool was[100500];

void dfs(int v, int p) {
     was[v] = true;
     tin[v] = fup[v] = timer++;
     for (int j = 0; j < a[v].size(); ++j) {
         int to = a[v][j];
         if (to == p) continue;
         if (was[to]) {
            fup[v] = min(fup[v], tin[to]);
         } else {
            dfs(to, v);
            fup[v] = min(fup[to], fup[v]);
            if (fup[to] > tin[v]) {
               ans[++kol] = w[v][j];
            }
         }
     }
}

int main() {
    freopen(fname".in", "r", stdin);
    freopen(fname".out", "w", stdout);
    int n, m;
    scanf("%d%d", &n, &m);
    for (int i = 1; i <= m; ++i) {
        int x,y;
        scanf("%d%d", &x, &y);
        a[x].push_back(y);
        a[y].push_back(x);
        w[x].push_back(i);
        w[y].push_back(i);
    }
    for (int i = 1; i <= n; ++i) {
        if (!was[i]) {
           dfs(i, -1);
        }
    }
    sort(ans + 1, ans + 1 + kol);
    printf("%d\n", kol);
    for (int i = 1; i <= kol; ++i) {
        printf("%d ", ans[i]);
    }
    return 0;
}