import sys
sys.setrecursionlimit(10**9)
N=int(input())
a,b=0,0
G=[[] for i in range(N)]
D=[-1]*N
for i in range(N):
  a,b=map(int,input().split())
  a,b=a-1,b-1
  G[a].append((b,i+1))
  G[b].append((a,i+1))
P=[]
def dfsr(n,x,y):
  global P
  for i in range(len(G[n])):
    if G[n][i][0]==x and D[n]==y:
      P.append(G[n][i][1])
      print(len(P))
      print(*P)
      exit()
    if D[n]+1==D[G[n][i][0]]:
      P.append(G[n][i][1])
      dfsr(G[n][i][0],x,y)

def dfs(n,p,d):
  if D[n]!=-1:
    dfsr(n,n,d-1)
  D[n]=d
  for i in range(len(G[n])):
    if G[n][i][0]!=p:
      dfs(G[n][i][0],n,d+1)

dfs(0,-1,0)