import times, strutils, sequtils, math, algorithm, tables, sets, lists, intsets
import critbits, future, strformat, deques
template `max=`(x,y) = x = max(x,y)
template `min=`(x,y) = x = min(x,y)
template `mod=`(x,y) = x = x mod y
template scan2 = (scan(), scan())
template scan3 = (scan(), scan())
let read* = iterator: string {.closure.} =
    while true: (for s in stdin.readLine.split: yield s)
proc scan(): int = read().parseInt
proc scanf(): float = read().parseFloat
proc toInt(c:char): int =
    return int(c) - int('0')




proc solve()=
  var
    n = scan()
    es = newseqwith(n,newseq[int]())
    
    loopE = newseqwith(n,newseq[bool]())
    invE = newseqwith(n,newseq[int]())
    ids = newseqwith(n,newseq[int]())
    touch = newseqwith(n,false)
  for i in 0..<n:
    var
      a = scan()-1
      b = scan()-1
    es[a].add(b)
    loopE[a].add(false)
    ids[a].add(i+1)
    es[b].add(a)
    loopE[b].add(false)
    ids[b].add(i+1)
    invE[a].add(es[b].len-1)
    invE[b].add(es[a].len-1)

  proc dfsFindLoop(par,p:int):int=
    result = -1
    if touch[p]:
      return p
    else:
      touch[p]=true
    for nIdx in 0..<es[p].len:
      var
        nxt = es[p][nIdx]
      if nxt == par:continue
      else:
        var t = dfsFindLoop(p,nxt)
        if t>=0:
          return t
    return -1


  proc dfs(par:int,p:int):bool=
    if touch[p]:
      return true
    else:
      touch[p]=true
    for nIdx in 0..<es[p].len:
      var
        nxt = es[p][nIdx]
      if nxt == par:continue
      else:
        var t = dfs(p,nxt)
        if t:
          loopE[p][nIdx]=true
          loopE[nxt][invE[p][nIdx]]=true
        result = result or t


  if es.anyIt(it.len>=3):
    var
      s = dfsFindLoop(-1,0)
      ans = inithashset[int]()
    touch.fill(false)
    discard dfs(-1,s)
    for p in 0..<n:
      for nIdx in 0..<es[p].len:
        if loopE[p][nIdx]:
          ans.incl(ids[p][nIdx])
    echo ans.len
    echo ans.toseq.join(" ")
    
    
    

  else:
    # 全部ループ
    var ans = newseq[int]()
    for i in 1..n:
      ans.add(i)
    echo n
    echo ans.join(" ")
      
     
solve()