#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i = 0; i < (n); i++)
typedef long long ll;
typedef long double ld;
typedef pair<int,int> P;

int main() {
  int n;
  cin >> n;
  vector<vector<int>> g(n);
  map<P, int> id;
  rep(i,n) {
    int a, b;
    cin >> a >> b;
    a--; b--;
    id[make_pair(a, b)] = i + 1;
    id[make_pair(b, a)] = i + 1;
    g[a].emplace_back(b);
    g[b].emplace_back(a);
  }

  vector<int> edge;
  vector<int> visited(n, 0);
  auto dfs = [&](auto& f, int p, int u)->int{
    if (visited[u]) {
      visited[u] = -1;
      return 0;
    }
    visited[u] = 1;
    for (auto v : g[u]) {
      if (v == p) continue;
      int ok = f(f, u, v);
      if (ok == 0) {
        edge.emplace_back(id[make_pair(u, v)]);
        if (visited[u] == -1) return -1;
        return 0;
      }
      if (ok == -1) return -1;
    }
    return 1;
  };
  dfs(dfs,-1,0);
  cout << edge.size() << endl;
  for (auto e : edge) cout << e << " ";
  cout << endl;
  return 0;
}