#include <bits/stdc++.h>
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define chmax(a, b) a = max(a, b)
#define chmin(a, b) a = min(a, b)
#define all(x) (x).begin(), (x).end()
using namespace std;
using ll = long long;
using P = pair<int,int>;
using VI = vector<int>;
using VVI = vector<VI>;


VVI to;
int n;
map<P, int> bmap;
VI parent, depth;
vector<int> ans;
bool dfs(int u, int d=0, int p=-1) {
    parent[u] = p;
    depth[u] = d;
    for(int v: to[u]) {
        if (v == p) continue;
        if (depth[v] == -1) {
            if (dfs(v, d+1, u)) return true;;
        } else {
            ans.push_back(bmap[{u, v}]);
            while(u != v) {
                if (depth[u] >= depth[v]) {
                    ans.push_back(bmap[{u, parent[u]}]);
                    u = parent[u];
                } else {
                    ans.push_back(bmap[{v, parent[v]}]);
                    v = parent[v];
                }
            }
            return true;
        }
    }
    return false;
}

int main() {
    cin >> n;
    to = VVI(n);
    depth = VI(n, -1);
    parent = VI(n, -1);
    rep(i, n) {
        int a, b;
        cin >> a >> b;
        a--; b--;
        bmap[{a, b}] = bmap[{b, a}] = i + 1;
        to[a].push_back(b);
        to[b].push_back(a);
    }
    dfs(0);
    sort(all(ans));
    cout << ans.size() << endl;
    rep(i, ans.size()) cout << ans[i] << " \n"[i + 1 == ans.size()];
}