import sys
input = sys.stdin.readline
from collections import deque
class LowLink:
  def __init__(self, N, M):
    self.V = N
    self.E = M
    self.edge = [[] for _ in range(self.V)]
    self.edges = [0]*M
    self.visited = [False]*N
    self.parent = [N]*N
    self.order = [N]*N
    self.low = [N]*N
    self.dic = dict()
  
  def add_edges(self, ind=1):
    for i in range(self.E):
      a,b = map(int, input().split())
      a -= ind
      b -= ind
      self.edge[a].append(b)
      self.edge[b].append(a)
      self.edges[i] = (a,b)
      self.dic[(a,b)] = i+1
      self.dic[(b,a)] = i+1

  def add_edge(self, a, b):
    self.edge[a].append(b)
    self.edge[b].append(a)

  def low_link(self, start):
    self.start = start
    stack = deque([start])
    self.parent[start] = -1
    self.order[start] = 0
    cnt = 1
    while stack:
      v = stack[-1]
      for u in self.edge[v]:
        if u==self.parent[v]:
          pass
        elif self.order[u]<self.order[v]: #後退辺の処理
          self.low[v] = min(self.low[v], self.order[u])
        elif self.parent[u]==N: #行きがけ
          self.order[u] = self.low[u] = cnt
          self.parent[u] = v
          stack.append(u)
          cnt += 1
          break
        else: #帰りがけ
          self.low[v] = min(self.low[v], self.low[u])
      else:
        stack.pop() #帰り
    return
  
  def bridge(self):
    res = []
    for a,b in self.edges:
      if G.order[a]>G.order[b]:
        a,b = b,a
      if G.low[b]<=G.order[a]:
        res.append(self.dic[(a,b)])
    return res
  
  def articulation(self):
    res = []
    for v in range(self.V):
      cnt = 0
      for u in self.edge[v]:
        if self.parent[v]==u or self.parent[u]!=v:
          continue
        if self.order[v]<=self.low[u]:
          cnt += 1
      if v==self.start:
        if cnt>=2:
          res.append(v)
      elif cnt>=1:
          res.append(v)
    return res


N = int(input())
G = LowLink(N, N)
G.add_edges(1)
G.low_link(0)
ans = G.bridge()
print(len(ans))
print(*ans)