package main import ( "bufio" "fmt" "os" "sort" "strconv" ) var sc = bufio.NewScanner(os.Stdin) var wr = bufio.NewWriter(os.Stdout) func out(x ...interface{}) { fmt.Fprintln(wr, x...) } func getI() int { sc.Scan() i, e := strconv.Atoi(sc.Text()) if e != nil { panic(e) } return i } func getF() float64 { sc.Scan() i, e := strconv.ParseFloat(sc.Text(), 64) if e != nil { panic(e) } return i } func getInts(N int) []int { ret := make([]int, N) for i := 0; i < N; i++ { ret[i] = getI() } return ret } func getS() string { sc.Scan() return sc.Text() } // min, max, asub, absなど基本関数 func max(a, b int) int { if a > b { return a } return b } func min(a, b int) int { if a < b { return a } return b } func asub(a, b int) int { if a > b { return a - b } return b - a } func abs(a int) int { if a >= 0 { return a } return -a } func lowerBound(a []int, x int) int { idx := sort.Search(len(a), func(i int) bool { return a[i] >= x }) return idx } func upperBound(a []int, x int) int { idx := sort.Search(len(a), func(i int) bool { return a[i] > x }) return idx } const mod = int(1e9 + 7) var cnt int func dfs(p, n int) int { if len(node[p]) == 0 { // out(p, n, 1) cnt += n * 1 cnt %= mod return 1 } ret := 1 for _, e := range node[p] { ret += dfs(e, n+1) } // out(p, n, ret) cnt += n * ret cnt %= mod return ret } var node [][]int func main() { defer wr.Flush() sc.Split(bufio.ScanWords) sc.Buffer([]byte{}, 1000000) // this template is new version. // use getI(), getS(), getInts(), getF() N := getI() node = make([][]int, N) sub := make([]int, N) for i := 0; i < N-1; i++ { from, to := getI()-1, getI()-1 node[from] = append(node[from], to) sub[to]++ } top := 0 for i := 0; i < N; i++ { if sub[i] == 0 { top = i } } dfs(top, 0) out(cnt) }