mod = 1000000007
eps = 10**-9


def main():
    import sys
    from collections import deque
    input = sys.stdin.buffer.readline

    class UnionFind():
        def __init__(self, n):
            self.n = n
            self.root = [-1] * (n + 1)
            self.rnk = [0] * (n + 1)

        def find_root(self, x):
            while self.root[x] >= 0:
                x = self.root[x]
            return x

        def unite(self, x, y):
            x = self.find_root(x)
            y = self.find_root(y)
            if x == y:
                return
            elif self.rnk[x] > self.rnk[y]:
                self.root[x] += self.root[y]
                self.root[y] = x
            else:
                self.root[y] += self.root[x]
                self.root[x] = y
                if self.rnk[x] == self.rnk[y]:
                    self.rnk[y] += 1

        def isSameGroup(self, x, y):
            return self.find_root(x) == self.find_root(y)

        def size(self, x):
            return -self.root[self.find_root(x)]

    N = int(input())
    E = []
    UF = UnionFind(N)
    aa = bb = 0
    ii = N+1
    adj = [[] for _ in range(N+1)]
    for i in range(1, N+1):
        a, b = map(int, input().split())
        E.append((a, b))
        if UF.isSameGroup(a, b):
            aa = a
            bb = b
            ii = i
        else:
            UF.unite(a, b)
            adj[a].append((b, i))
            adj[b].append((a, i))

    que = deque()
    que.append(1)
    seen = [-1] * (N+1)
    seen[1] = 0
    par = [0] * (N+1)
    while que:
        v = que.popleft()
        for u, e in adj[v]:
            if seen[u] == -1:
                seen[u] = seen[v] + 1
                par[u] = (v, e)
                que.append(u)

    ans = {ii}
    v = aa
    while v != 1:
        p, e = par[v]
        ans.add(e)
        v = p
    v = bb
    while v != 1:
        p, e = par[v]
        if e in ans:
            ans.discard(e)
        else:
            ans.add(e)
        v = p
    print(len(ans))
    print(*ans)


if __name__ == '__main__':
    main()