N = int(input())
AB = [list(map(int,input().split())) for _ in range(N)]
E = [set() for _ in range(N)]
for i, (a, b) in enumerate(AB):
    a -= 1
    b -= 1
    E[a].add((b,i))
    E[b].add((a,i))
Q = []
for x in range(N):
    if len(E[x]) == 1:
        Q.append(x)
ans = set(range(1,N+1))
while Q:
    x = Q.pop()
    for y,i in E[x]:
        E[y].remove((x,i))
        ans.remove(i + 1)
        if len(E[y]) == 1:
            Q.append(y)
print(len(ans))
print(*ans)