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

  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 bfs(self, start):
    stack = deque([start])
    self.parent[start] = -1
    while stack:
      v = stack.pop()
      for u in self.edge[v]:
        if u==self.parent[v]:
          continue
        if self.parent[u]!=N:
          return v,u
        self.parent[u]=v
        #頂点に対する処理
        stack.append(u)
    return

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())
  a,b = min(a-1,b-1), max(a-1,b-1)
  G.add_edge(a,b,i+1)
  G.add_edge(b,a,i+1)

v,u = G.bfs(0)
ans = [G.edges[v,u]]
while G.parent[v]!=-1:
  ans.append(G.edges[(G.parent[v],v)])
  v = G.parent[v]
while G.parent[u]!=-1:
  ans.append(G.edges[(G.parent[u],u)])
  u = G.parent[u]
print(len(ans))
print(*ans)