import sys
input = sys.stdin.readline
sys.setrecursionlimit(10**5+10)
from collections import *

def dfs(v, pv):
    global pos
    
    seen[v] = True
    hist.append(v)
    
    for nv in G[v]:
        if nv==pv:
            continue
        
        if finished[nv]:
            continue
        
        if seen[nv] and not finished[nv]:
            pos = nv
            return
        
        dfs(nv, v)
        
        if pos!=-1:
            return
    
    hist.pop()
    finished[v] = True

N = int(input())
G = [[] for _ in range(N)]
edges = defaultdict(int)

for i in range(N):
    a, b = map(int, input().split())
    G[a-1].append(b-1)
    G[b-1].append(a-1)
    edges[(min(a-1, b-1), max(a-1, b-1))] = i

pos = -1
seen = [False]*N
finished = [False]*N
hist = []
dfs(0, -1)
ans = []

for i in range(len(hist)):
    u, v = hist[i], hist[(i+1)%len(hist)]
    u, v = min(u, v), max(u, v)
    ans.append(edges[(u, v)]+1)

print(len(ans))
print(*ans)