import sys
def I(): return int(sys.stdin.readline().rstrip())
def MI(): return map(int,sys.stdin.readline().rstrip().split())


N = I()
Graph = [[] for _ in range(N+1)]
dict_edge = {}
for i in range(1,N+1):
    a,b = MI()
    Graph[a].append(b)
    Graph[b].append(a)
    dict_edge[(a,b)] = i
    dict_edge[(b,a)] = i

flag = [0]*(N+1)
previous = [0]*(N+1)
ANS = []


def dfs(i,par):
    flag[i] = 1
    for j in Graph[i]:
        if j == par:
            continue
        elif flag[j] == 0:
            flag[j] = 1
            previous[j] = i
            dfs(j,i)
        else:
            ANS.append(dict_edge[(i,j)])
            k = i
            while k != j:
                ANS.append(dict_edge[k,previous[k]])
                k = previous[k]
        break


dfs(1,0)
print(len(ANS))
print(*ANS)