import sys
import sys;input=sys.stdin.readline
sys.setrecursionlimit(10**5+1)
# 単純に橋となる辺を返す
def bridge(G, N):
    result = set()
    label = [None]*N
    gen = 0
    cost = [0]*N
    def dfs(u, p):
        nonlocal gen
        res = 0
        for v in G[u]:
            if v == p:
                continue
            if label[v] is not None:
                if label[v] < label[u]:
                    cost[v] += 1
                    res += 1
            else:
                label[v] = gen; gen += 1
                r = dfs(v, u)
                if r == 0:
                    result.add((u, v))
                res += r
        res -= cost[u]
        return res
    for v in range(N):
        if not label[v]:
            label[v] = gen; gen += 1
            r = dfs(v, -1)
            assert r == 0, r
    return result
N, = map(int, input().split())
G = [[] for _ in range(N)]
E = dict()
for i in range(N):
    a, b = map(int, input().split())
    G[a-1].append(b-1)
    G[b-1].append(a-1)
    E[(a-1, b-1)] = i+1
    E[(b-1, a-1)] = i+1
es = set([E[x] for x in bridge(G, N)])
R =[i for i in range(1, N+1) if i not in es]
print(len(R))
print(*R)