import sys
sys.setrecursionlimit(10**6)
N = int(input())
G = {i:[] for i in range(1,N+1)}
E = {}
for i in range(1,N+1):
    a,b = map(int,input().split())
    G[a].append(b)
    G[b].append(a)
    E[(a,b)] = i
    E[(b,a)] = i
A = [0]*(N+1)
def dfs(v,p):
    for u in G[v]:
        if u==p:
            continue
        if A[u]==0:
            A[u] = A[v]+1
            res = dfs(u,v)
            if res!=None:
                return res
            A[u] = 0
        else:
            return u
A[1] = 1
s = dfs(1,0)
ans = []
p = 0
x = s
flag = False
while True:
    for u in G[x]:
        if u==p:continue
        if u==s:
            ans.append(E[(x,u)])
            flag = True
            break
        if A[u]==A[x]+1:
            ans.append(E[(x,u)])
            p = x
            x = u
            break
    if flag:break
print(len(ans))
print(*ans)