from collections import defaultdict
from typing import List
import sys
sys.setrecursionlimit(10**8)
import pypyjit
pypyjit.set_param("max_unroll_recursion=-1")
input = sys.stdin.readline

class UnionFind:
    """0-indexed"""
    def __init__(self, n):
        self.n = n
        self.parent = [-1] * n
        self.__group_count = n

    def unite(self, x, y) -> bool:
        """xとyをマージ"""
        x = self.root(x)
        y = self.root(y)
        if x == y:
            return False

        self.__group_count -= 1

        if self.parent[x] > self.parent[y]:
            x, y = y, x

        self.parent[x] += self.parent[y]
        self.parent[y] = x
        return True

    def is_same(self, x, y) -> bool:
        """xとyが同じ連結成分か判定"""
        return self.root(x) == self.root(y)

    def root(self, x) -> int:
        """xの根を取得"""
        if self.parent[x] < 0:
            return x
        else:
            # 経路圧縮あり
            # self.parent[x] = self.root(self.parent[x])
            # return self.parent[x]
            # 経路圧縮なし
            return self.root(self.parent[x])

    def size(self, x) -> int:
        """xが属する連結成分のサイズを取得"""
        return -self.parent[self.root(x)]

    def all_sizes(self) -> List[int]:
        """全連結成分のサイズのリストを取得 O(N)"""
        sizes = []
        for i in range(self.n):
            size = self.parent[i]
            if size < 0:
                sizes.append(-size)
        return sizes
    
    def members(self, x) -> List[int]:
        """xが属するグループのリストを返す O(N)"""
        mem = []
        r = self.root(x)
        for i in range(self.n):
            if self.root(i) == r:
                mem.append(i)
        return mem

    def groups(self) -> List[List[int]]:
        """全連結成分の内容のリストを取得 O(N・α(N))"""
        groups = dict()
        for i in range(self.n):
            p = self.root(i)
            if not groups.get(p):
                groups[p] = []
            groups[p].append(i)
        return list(groups.values())

    @property
    def group_count(self) -> int:
        """連結成分の数を取得 O(1)"""
        return self.__group_count

N = int(input())
uf = UnionFind(N)
G = [list() for _ in range(N)]
def dfs(v,p,start,f,edge):
    if v==start and f==True:
        return True
    elif v==start:
        f = True
    if len(G[v])==1:
        return False
    for nex in G[v]:
        if nex==p:
            continue
        if dfs(nex,v,start,f,edge):
            edge.append((nex,v))
            return True

d = defaultdict(int)
for i in range(N):
    a, b = map(int, input().split())
    a-=1;b-=1
    G[a].append(b)
    G[b].append(a)
    d[str(a)+'_'+str(b)] = i+1
    d[str(b)+'_'+str(a)] = i+1
    if uf.is_same(a,b):
        edge = []
        dfs(a,b,a,False,edge)
        print(len(edge))
        ans = []
        for u,v in edge:
            ans.append(d[str(u)+'_'+str(v)])
        ans.sort()
        print(*ans)

    else:
        uf.unite(a,b)