import sys
sys.setrecursionlimit(10**6)
def input():
	return sys.stdin.buffer.readline()[:-1]

n = int(input())
adj = [[] for _ in range(n)]
prev = [(-1, -1) for _ in range(n)]
vstd = [False for _ in range(n)]
for i in range(n):
	a, b = map(int, input().split())
	adj[a-1].append((b-1, i+1))
	adj[b-1].append((a-1, i+1))

def dfs(i, p):
	for j, e in adj[i]:
		if j == p:
			continue
		if not vstd[j]:
			vstd[j] = True
			prev[j] = (i, e)
			dfs(j, i)
		else:
			ans = [e]
			cur = i
			while True:
				ans.append(prev[cur][1])
				cur = prev[cur][0]
				if cur == j:
					print(len(ans))
					print(*ans)
					sys.exit()
					break
	return

vstd[0] = True
dfs(0, -1)