#define PROBLEM "https://yukicoder.me/problems/no/1254"

#include <bits/stdc++.h>
using namespace std;
template <class T> using V = vector<T>;
using ll = long long;
#define REP(i,n) for(ll i=0; i<ll(n); i++)

V<int> namori_loop(const V<V<int>>& g) {
  V<int> roots;
  V<int> seen(g.size());
  int st;
  auto dfs = [&](auto&& self, int u, int p) -> bool {
    seen[u] = 1;
    for(int v : g[u]) {
      if(v == p) continue;
      if(seen[v]) {
        st = v;
        roots.push_back(u);
        return true;
      }
      if(self(self, v, u)) {
        roots.push_back(u);
        return u != st;
      }
    }
    return false;
  };
  dfs(dfs, 0, -1);
  return roots;
};


int main() {
    int n; cin >> n;
    V<V<int>> g(n);
    map<pair<int, int>, int> eid;
    REP(i, n) {
        int a, b; cin >> a >> b; a--; b--;
        g[a].push_back(b);
        g[b].push_back(a);
        eid[{a, b}] = eid[{b, a}] = i;
    }
    V<int> loop = namori_loop(g);
    int m = loop.size();
    cout << m << endl;
    REP(i, m) {
        cout << eid[{loop[i], loop[(i+1)%m]}]+1 << " \n"[i==m-1];
    }
}