lib C
  fun strtoll(s : UInt8*, p : UInt8**, b : Int32) : Int64
end

class String
  def to_i64
    C.strtoll(self, nil, 10)
  end
end

class Solve
  @n : Int32
  @g = Array(Array(Tuple(Int32, Int32))).new
  @edges = [] of Tuple(Int32, Int32)
  @in_loop : Int32?

  def initialize
    @n = read_line.to_i
    @g = (1..@n).map { Array(Tuple(Int32, Int32)).new }
    @n.times do |i|
      a, b = read_line.split.map(&.to_i.pred)
      @g[a] << {b, i}
      @g[b] << {a, i}
      @edges << {a, b}
    end
    @flag = Array(Int32?).new(@n, nil)
  end

  def dfs(v, prev, prev_edge)
    if @flag[v]
      @in_loop = v
      @flag[v] = prev_edge
      return
    end
    @flag[v] = prev_edge
    @g[v].each do |(u, i)|
      next if u == prev || @in_loop
      dfs(u, v, i)
    end
  end

  def solve
    dfs(0, -1, -1)
    ans = [] of Int32
    now = @in_loop.not_nil!
    while now != @in_loop || ans.empty?
      edge_i = @flag[now].not_nil!
      ans << edge_i + 1
      u, v = @edges[edge_i]
      now = u == now ? v : u
    end
    puts ans.size, ans.sort.join(' ')
  end
end

solve = Solve.new
solve.solve