package main import ( "bufio" "fmt" "os" "strconv" ) func configure(scanner *bufio.Scanner) { scanner.Split(bufio.ScanWords) scanner.Buffer(make([]byte, 1000005), 1000005) } func getNextString(scanner *bufio.Scanner) string { scanned := scanner.Scan() if !scanned { panic("scan failed") } return scanner.Text() } func getNextInt(scanner *bufio.Scanner) int { i, _ := strconv.Atoi(getNextString(scanner)) return i } func getNextInt64(scanner *bufio.Scanner) int64 { i, _ := strconv.ParseInt(getNextString(scanner), 10, 64) return i } func getNextFloat64(scanner *bufio.Scanner) float64 { i, _ := strconv.ParseFloat(getNextString(scanner), 64) return i } func main() { fp := os.Stdin wfp := os.Stdout extra := 0 if os.Getenv("I") == "IronMan" { fp, _ = os.Open(os.Getenv("END_GAME")) extra = 100 } scanner := bufio.NewScanner(fp) configure(scanner) writer := bufio.NewWriter(wfp) defer func() { r := recover() if r != nil { fmt.Fprintln(writer, r) } writer.Flush() }() solve(scanner, writer) for i := 0; i < extra; i++ { fmt.Fprintln(writer, "-----------------------------------") solve(scanner, writer) } } func solve(scanner *bufio.Scanner, writer *bufio.Writer) { n := getNextInt(scanner) g := newGraph(n) for i := 0; i < n; i++ { a := getNextInt(scanner) - 1 b := getNextInt(scanner) - 1 g.AppendEdge(a, b, i) g.AppendEdge(b, a, i) } var dfs func(int, int) bb := map[int]bool{} dfs = func(now, p int) { if g.v[now].visit { return } g.v[now].visit = true g.v[now].deg = 1 for _, e := range g.e[now] { if e.to == p { continue } if !g.v[e.to].visit { dfs(e.to, now) } if g.v[e.to].deg == 0 { bb[e.id] = true } g.v[now].deg += g.v[e.to].deg } if g.v[now].deg == 1 { g.v[now].deg-- } } dfs(0, -1) fmt.Fprintln(writer, n-len(bb)) sep := "" for i := 0; i < n; i++ { if bb[i] { continue } fmt.Fprintf(writer, "%s%d", sep, i+1) sep = " " } fmt.Fprintln(writer, "") } type vertex struct { visit bool deg int } type edge struct { to, id int } type graph struct { v []vertex e [][]edge } func newGraph(n int) graph { return graph{ v: make([]vertex, n), e: make([][]edge, n), } } func (g *graph) AppendEdge(from, to, id int) { g.e[from] = append(g.e[from], edge{ to: to, id: id, }) }