n = int(input())
to = [[] for _ in range(n)]
bmap = {}
for i in range(1, n+1):
    a, b = map(int, input().split())
    a -= 1
    b -= 1
    to[a].append(b)
    to[b].append(a)
    bmap[(a, b)] = bmap[(b, a)] = i

num = [-1] * n
low = [-1] * n
visited = [False] * n
ans = 0
nm = 1
def dfs(v, p=-1):
    global nm
    visited[v] = True
    num[v] = nm
    nm += 1
    lw = num[v]
    for w in to[v]:
        if w == p:
            continue
        if not visited[w]:
            dfs(w, v)
            lw = min(lw, low[w])
        else:
            lw = min(lw, num[w])
    low[v] = lw
dfs(0)
ans = set(range(1, n+1))
visited = [False] * n
def dfs2(v, p=-1):
    visited[v] = True
    for w in to[v]:
        if w == p:
            continue
        if not visited[w]:
            dfs2(w)
            if low[w] > num[v]:
                ans.remove(bmap[(v, w)])
dfs2(0)
print(len(ans))
print(*ans)