import sys,os,io
input = sys.stdin.readline
class Graph:
  def __init__(self, N):
    self.V = N
    self.edge = [[] for _ in range(self.V)]
    self.edges = [0]*(N*2+1)
    self.visited = [0]*N
    self.parent = [N]*N
  
  def add_edge(self, a, b, i):
    self.edge[a].append((b,i))
    self.edges[i] = (a,b)

  def dfs(self, start):
    stack = [start]
    self.parent[start] = -1
    self.visited[start] = 1
    #記録したい値の配列を定義
    while stack:
      v = stack[-1]
      for u,i in self.edge[v]:
        if u==self.parent[v]:
          continue
        if self.parent[u]==N: #子へ降ろす
          self.parent[u]=v
          stack.append(u)
          break
        else:
          return u
      else:
        stack.pop()

  def bfs1(self, start):
    stack = [start]
    self.parent[start] = -1
    while stack:
      v = stack.pop()
      for u,i in self.edge[v]:
        if u==self.parent[v]:
          continue
        if self.parent[u]!=N:
          return u
        self.parent[u]=v
        #頂点に対する処理
        stack.append(u)
    return
  
  
  def bfs(self, start):
    d = deque()
    d.append(dict())
    cyc = dict()
    cnt = 0
    while len(d)>0 and cnt<N+1:
      es = d.popleft()
      if len(es):
        v0,v = self.edges[list(es.keys())[-1]]
      else:
        v0,v = start,start
      for w,i in self.edge[v]:
        if w==v0:
          continue
        if i not in es:
          dic = copy(es)
          dic[i] = True
          if w==start:
            for i in range(N+1,2*N+1):
              if i in dic:
                dic[i-N] = True
                del dic[i]
            if len(dic)>len(cyc):
              cyc = dic
          else:
            d.append(dic)
      cnt += 1
    return cyc

from collections import deque
from copy import copy

N = int(input())
G = Graph(N)
for i in range(N):
  a,b = map(int, input().split())
  G.add_edge(a-1,b-1,i+1)
  G.add_edge(b-1,a-1,N+i+1)

ans = set()
cyc = G.bfs1(0)
es = G.bfs(cyc)
for e in es.keys():
  ans.add(e)
ans = list(ans)
print(len(ans))
print(*ans)