import sys
input = sys.stdin.buffer.readline
sys.setrecursionlimit(10 ** 7)

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


bridge = [0] * N
vis = [0] * N
entry = [-1] * N
low = [-1] * N
time = 0


def dfs(s, p=-1):
    global time
    vis[s] = 1
    entry[s] = time
    low[s] = time
    time += 1
    for t, i in G[s]:
        if t == p:
            continue
        if vis[t]:
            low[s] = min(low[s], entry[t])
        else:
            dfs(t, s)
            low[s] = min(low[s], low[t])
            if entry[s] < low[t]:
                bridge[i] = 1


dfs(0)
ans = [i for i, b in enumerate(bridge, 1) if b == 0]
print(len(ans))
print(*ans)