/* -*- coding: utf-8 -*-
 *
 * 1254.cc:  No.1254 補強への架け橋 - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

const int MAX_N = 100000;

/* typedef */

typedef pair<int,int> pii;
typedef vector<pii> vpii;

/* global variables */

vpii nbrs[MAX_N];
int ps[MAX_N], ds[MAX_N], cis[MAX_N];
int es[MAX_N];

/* subroutines */

/* main */

int main() {
  int n;
  scanf("%d", &n);

  for (int i = 0; i < n; i++) {
    int a, b;
    scanf("%d%d", &a, &b);
    a--, b--;
    nbrs[a].push_back(pii(b, i));
    nbrs[b].push_back(pii(a, i));
  }

  memset(ds, -1, sizeof(ds));
  ps[0] = -1, ds[0] = 1;

  int l = -1, r = -1;
  for (int u = 0; u >= 0;) {
    if (cis[u] < nbrs[u].size() && nbrs[u][cis[u]].first == ps[u])
      cis[u]++;
    if (cis[u] < nbrs[u].size()) {
      pii a = nbrs[u][cis[u]++];
      int v = a.first, ei = a.second;
      es[ds[u]] = ei;
      if (ds[v] < 0) {
	ps[v] = u, ds[v] = ds[u] + 1;
	u = v;
      }
      else {
	l = ds[v], r = ds[u] + 1;
	break;
      }
    }
    else
      u = ps[u];
  }
  //printf("l=%d, r=%d\n", l, r);

  printf("%d\n", r - l);
  for (int i = l; i < r; i++) {
    printf("%d", es[i] + 1);
    putchar(i + 1 < r ? ' ' : '\n');
  }
  return 0;
}