class UnionFind():
    def __init__(self, n):
        self.n = n
        self.parents = [-1] * n
        self.group = n

    def find(self, x):
        if self.parents[x] < 0:
            return x
        else:
            self.parents[x] = self.find(self.parents[x])
            return self.parents[x]

    def union(self, x, y):
        x = self.find(x)
        y = self.find(y)

        if x == y:
            return
        self.group -= 1
        if self.parents[x] > self.parents[y]:
            x, y = y, x

        self.parents[x] += self.parents[y]
        self.parents[y] = x

    def size(self, x):
        return -self.parents[self.find(x)]

    def same(self, x, y):
        return self.find(x) == self.find(y)

    def members(self, x):
        root = self.find(x)
        return [i for i in range(self.n) if self.find(i) == root]

    def roots(self):
        return [i for i, x in enumerate(self.parents) if x < 0]

    def group_count(self):
        return self.group

    def all_group_members(self):
        dic = {r:[] for r in self.roots()}
        for i in range(self.n):
            dic[self.find(i)].append(i)
        return dic

    def __str__(self):
        return '\n'.join('{}: {}'.format(r, self.members(r)) for r in self.roots())

n = int(input())
edges = [[] for _ in range(n)]
UF = UnionFind(n)

for i in range(1, n + 1):
    a, b = map(int, input().split())
    a -= 1
    b -= 1
    if UF.same(a, b):
        aa, bb, ii = a, b, i
    else:
        UF.union(a, b)
        edges[a].append((b, i))
        edges[b].append((a, i))

used = [False] * n
used[0] = 0
stack = [0]
parent = [-1] * n
bind = [-1] * n
dist = [0] * n

while stack:
    pos = stack.pop()
    for npos, i in edges[pos]:
        if used[npos]:
            continue
        used[npos] = True
        bind[npos] = i
        dist[npos] = dist[pos] + 1
        parent[npos] = pos
        stack.append(npos)

ans = [ii]
if dist[aa] < dist[bb]:
    aa, bb = bb, aa
while dist[aa] != dist[bb]:
    ans.append(bind[aa])
    aa = parent[aa]

while aa != bb:
    ans.append(bind[aa])
    aa = parent[aa]
    ans.append(bind[bb])
    bb = parent[bb]

print(len(ans))
print(*ans)