package main

import (
  "bufio"
  "os"
  "strconv"
  "strings"
  "fmt"
  "container/heap"
)

var reader = bufio.NewReaderSize(os.Stdin, 1000000)
var writer = bufio.NewWriter(os.Stdout)
func NextLine() string {
  buffer := make([]byte, 0)
  for true {
    line, isPrefix, err := reader.ReadLine()
    if err != nil { panic(err) }
    buffer = append(buffer, line...)
    if !isPrefix { break }
  }
  return string(buffer)
}
func NextInt(A ...*int) {
  L := strings.Split(NextLine(), " ")
  for i, a := range A {
    *a, _ = strconv.Atoi(L[i])
  }
}
func NextIntVec(A *[]int) {
  L := strings.Split(NextLine(), " ")
  (*A) = make([]int, len(L))
  for i, l := range L {
    (*A)[i], _ = strconv.Atoi(l)
  }
}
func NextFloat(A ...*float64) {
  L := strings.Split(NextLine(), " ")
  for i, a := range A {
    *a, _ = strconv.ParseFloat(L[i], 64)
  }
}
func NextFloatVec(A *[]float64) {
  L := strings.Split(NextLine(), " ")
  (*A) = make([]float64, len(L))
  for i, l := range L {
    (*A)[i], _ = strconv.ParseFloat(l, 64)
  }
}
func Write(s interface{}) {
  fmt.Fprintln(writer, s)
}
func WriteIntVec(A []int) {
  S := make([]string, len(A))
  for i, a := range A {
    S[i] = strconv.Itoa(a)
  }
  Write(strings.Join(S, " "))
}
func Output() {
  _ = writer.Flush()
}

func MaxInt(A ...int) int {
  max := A[0]
  for _, a := range A {
    if max < a { max = a }
  }
  return max
}
func MinInt(A ...int) int {
  min := A[0]
  for _, a := range A {
    if a < min { min = a }
  }
  return min
}
func SumInt(A ...int) int {
  sum := 0
  for _, a := range A {
    sum += a
  }
  return sum
}
func Abs(x int) int {
  if x < 0 { x = -x }
  return x
}

type Item struct {
  Priority int
  Entry interface{}
}
type Heap []*Item
func (H Heap) Len() int { return len(H) }
func (H Heap) Less(i, j int) bool { return H[i].Priority < H[j].Priority }
func (H Heap) Swap(i, j int) { H[i], H[j] = H[j], H[i] }
func (H *Heap) Pop() interface{} {
  Old := *H
  n := len(Old)
  item := Old[n - 1]
  *H = Old[0:n - 1]
  return item
}
func (H *Heap) Push(x interface{}) {
  item := x.(*Item)
  *H = append(*H, item)
}
type PriorityQueue struct {
  Comparator func(e interface{}) int
  Items Heap
}
func (PQ *PriorityQueue) Push(e interface{}) {
  item := Item{PQ.Comparator(e), e}
  heap.Push(&PQ.Items, &item)
}
func (PQ *PriorityQueue) Pop() interface{} {
  return heap.Pop(&PQ.Items).(*Item).Entry
}
func InitPQ(F func(interface{}) int) PriorityQueue {
  var H Heap
  return PriorityQueue{F, H}
}

func WeightedDijkstra(G *[][][]int, s int) []int {
  N := len((*G))
  D := make([]int, N)
  for i := range D {
    D[i] = p * N
  }
  F := func(e interface{}) int { return e.([]int)[1] }
  PQ := InitPQ(F)
  PQ.Push([]int{s, 0})
  for 0 < PQ.Items.Len() {
    pq := PQ.Pop().([]int)
    u, dist := pq[0], pq[1]
    if D[u] < dist { continue }
    D[u] = dist
    for _, adj := range (*G)[u] {
      v, d := adj[0], adj[1]
      if D[v] <= D[u] + d { continue }
      D[v] = D[u] + d
      PQ.Push([]int{v, D[u] + d})
    }
  }
  return D
}

const p = 1000000007

func Solve() {
  var N, M int
  NextInt(&N, &M)
  G := make([][][]int, N)
  for i := range G {
    G[i] = make([][]int, 0)
  }
  var S, T int
  NextInt(&S, &T)
  S--
  T--
  E := make([][]int, M)
  var u, v, d int
  for i := range E {
    NextInt(&u, &v, &d)
    u--
    v--
    G[u] = append(G[u], []int{v, d})
    G[v] = append(G[v], []int{u, d})
    E[i] = []int{u, v, d}
  }
  D1 := WeightedDijkstra(&G, S)
  F := func(e interface{}) int { return e.([]int)[1] }
  PQ := InitPQ(F)
  for i, d := range D1 {
    PQ.Push([]int{i, d})
  }
  D := make([]int, N)
  for i := range D {
    D[i] = PQ.Pop().([]int)[0]
  }
  DP1 := make([]int, N)
  DP1[S] = 1
  for i := 0; i < N; i++ {
    u := D[i]
    for _, adj := range G[u] {
      v, d := adj[0], adj[1]
      if D1[v] - D1[u] != d { continue }
      DP1[v] = (DP1[v] + DP1[u]) % p
    }
  }
  //D2 := WeightedDijkstra(&G, T)
  DP2 := make([]int, N)
  DP2[T] = 1
  for i := N - 1; 0 <= i; i-- {
    u := D[i]
    for _, adj := range G[u] {
      v, d := adj[0], adj[1]
      if D1[u] - D1[v] != d { continue }
      DP2[v] = (DP2[v] + DP2[u]) % p
    }
  }
  cnt := DP1[T] * DP1[T] % p
  for i := range D1 {
    //if D1[i] != D2[i] { continue }
    if 2 * D1[i] != D1[T] { continue }
    x := DP1[i] * DP2[i] % p
    cnt = (p + cnt - (x * x % p)) % p
  }
  for _, e := range E {
    u, v, d := e[0], e[1], e[2]
    if D1[v] < D1[u] { u, v = v, u }
    if D1[v] - D1[u] != d { continue }
    //if D2[u] - D2[v] != d { continue }
    if D1[T] <= 2 * D1[u] || 2 * D1[v] <= D1[T] { continue }
    //if D2[S] <= 2 * D2[v] || 2 * D2[u] <= D2[S] { continue }
    x := DP1[u] * DP2[v] % p
    cnt = (p + cnt - (x * x % p)) % p
  }
  Write(cnt)
  return
}

func main() {
  Solve()
  Output()
}

Measured memory_bytes: 69376