#include <bits/stdc++.h>

using namespace std;
typedef long long ll;
typedef pair<ll, ll> p_ll;

template<class T>
void debug(T itr1, T itr2) { auto now = itr1; while(now<itr2) { cout << *now << " "; now++; } cout << endl; }
#define repr(i,from,to) for (ll i=(ll)from; i<(ll)to; i++)
#define all(vec) vec.begin(), vec.end()
#define rep(i,N) repr(i,0,N)
#define per(i,N) for (int i=(int)N-1; i>=0; i--)

const ll MOD = pow(10,9)+7;
const ll LLINF = pow(2,61)-1;
const int INF = pow(2,30)-1;

vector<ll> fac;
void c_fac(int x=pow(10,6)+10) { fac.resize(x,true); rep(i,x) fac[i] = i ? (fac[i-1]*i)%MOD : 1; }
ll inv(ll a, ll m=MOD) { ll b = m, x = 1, y = 0; while (b!=0) { int d = a/b; a -= b*d; swap(a,b); x -= y*d; swap(x,y); } return (x+m)%m; }
ll nck(ll n, ll k) { return fac[n]*inv(fac[k]*fac[n-k]%MOD)%MOD; }
ll gcd(ll a, ll b) { if (a<b) swap(a,b); return b==0 ? a : gcd(b, a%b); }
ll lcm(ll a, ll b) { return a/gcd(a,b)*b; }

vector<vector<ll>> adj;
vector<ll> p;
ll last = -1;

void dfs(ll n=0) {
  for (auto x: adj[n]) {
    if (x==p[n]||last!=-1) continue;
    if (p[x]!=-1) { p[x] = n; last = n; break; }
    else { p[x] = n; dfs(x); }
  }
}

int main() {
  ll N; cin >> N;
  adj.resize(N); p.resize(N,-1);
  ll a[N], b[N]; rep(i,N) { cin >> a[i] >> b[i]; a[i]--; b[i]--; }
  rep(i,N) { adj[a[i]].push_back(b[i]); adj[b[i]].push_back(a[i]); }
  dfs();
  // cout << last << endl; debug(all(p));

  vector<bool> lp(N);  
  ll np = last; do { lp[np] = true; np = p[np]; } while (np!=last);

  vector<ll> result; rep(i,N) if (lp[a[i]]&&lp[b[i]]) result.push_back(i+1);
  cout << result.size() << endl;
  debug(all(result)); 
  return 0;
}