object Main {
  import java.io.{BufferedReader, InputStream, InputStreamReader}
  import java.util.StringTokenizer
  import scala.reflect.ClassTag

  def main(args: Array[String]): Unit = {
    val out = new java.io.PrintWriter(System.out)
    new Main(out, new InputReader(System.in)).solve()
    out.flush()
  }

  private val oj = System.getenv("ATCODER_DEBUG") == null
  def DEBUG(f: => Unit): Unit = {
    if (!oj){ f }
  }
  def debug(as: Array[Boolean]): Unit = if (!oj){ debug(as.map(x => if(x) "1" else "0").mkString) }
  def debug(as: Array[Int]): Unit = if (!oj){ debug(as.mkString(" ")) }
  def debug(as: Array[Long]): Unit =if (!oj){ debug(as.mkString(" ")) }
  def debugDim(m: Array[Array[Long]]): Unit = if (!oj){
    REP(m.length) { i =>
      debug(m(i))
    }
  }
  def debugDimFlip(m: Array[Array[Long]]): Unit = if (!oj){
    REP(m(0).length) { j =>
      REP(m.length) { i =>
        System.err.print(m(i)(j))
        System.err.print(" ")
      }
      System.err.println()
    }
  }
  def debug(s: => String): Unit = DEBUG {
    System.err.println(s)
  }
  def debugL(num: => Long): Unit = DEBUG {
    System.err.println(num)
  }

  class InputReader(val stream: InputStream) {
    private val reader = new BufferedReader(new InputStreamReader(stream), 32768)
    private var tokenizer: StringTokenizer = _

    def next(): String = {
      while (tokenizer == null || !tokenizer.hasMoreTokens)
        tokenizer = new StringTokenizer(reader.readLine)
      tokenizer.nextToken
    }

    def nextInt(): Int = Integer.parseInt(next())
    def nextLong(): Long = java.lang.Long.parseLong(next())
    def nextChar(): Char = next().charAt(0)

    def ni(): Int = nextInt()
    def nl(): Long = nextLong()
    def nc(): Char = nextChar()
    def ns(): String = next()
    def ns(n: Int): Array[Char] = ns().toCharArray
    def na(n: Int, offset: Int = 0): Array[Int] = map(n)(_ => ni() + offset)
    def na2(n: Int, offset: Int = 0): (Array[Int], Array[Int]) = {
      val A1, A2 = Array.ofDim[Int](n)
      REP(n) { i =>
        A1(i) = ni() + offset
        A2(i) = ni() + offset
      }
      (A1, A2)
    }
    def nm(n: Int, m: Int): Array[Array[Int]] = {
      val A = Array.ofDim[Int](n, m)
      REP(n) { i =>
        REP(m) { j =>
          A(i)(j) = ni()
        }
      }
      A
    }
    def nal(n: Int): Array[Long] = map(n)(_ => nl())
    def nm_c(n: Int, m: Int): Array[Array[Char]] = map(n) (_ => ns(m))
  }

  def REP(n: Int, offset: Int = 0)(f: Int => Unit): Unit = {
    var i = offset
    val N = n + offset
    while(i < N) { f(i); i += 1 }
  }
  def REP_r(n: Int, offset: Int = 0)(f: Int => Unit): Unit = {
    var i = n - 1 + offset
    while(i >= offset) { f(i); i -= 1 }
  }
  def TO(from: Int, to: Int)(f: Int => Unit): Unit = {
    REP(to - from + 1, from) { i =>
      f(i)
    }
  }
  def map[@specialized A: ClassTag](n: Int, offset: Int = 0)(f: Int => A): Array[A] = {
    val res = Array.ofDim[A](n)
    REP(n)(i => res(i) = f(i + offset))
    res
  }

  def sumL(as: Array[Int]): Long = {
    var s = 0L
    REP(as.length)(i => s += as(i))
    s
  }
  def cumSum(as: Array[Int]): Array[Long] = {
    val cum = Array.ofDim[Long](as.length + 1)
    REP(as.length) { i =>
      cum(i + 1) = cum(i) + as(i)
    }
    cum
  }
}

class Main(out: java.io.PrintWriter, sc: Main.InputReader) {
  import sc._
  import Main._
  import java.util.Arrays.sort

  import scala.collection.mutable
  import math.{abs, max, min}
  import mutable.ArrayBuffer

  // toIntとか+7とかするならvalにしろ
  @inline private def MOD = 1000000007

  def solve(): Unit = {
    val N, M = ni()
    val P, Q = ni() - 1
    val T = ni()
    val from, to, w = Array.ofDim[Int](M)
    REP(M) { i =>
      val a, b = ni() - 1
      val c = ni()
      from(i) = a
      to(i) = b
      w(i) = c
    }
    val g = packWUGraph(N, from, to, w)
    val D = map(N)(dijk(g, _))

    var ans = -1L
    if (D(0)(P) + D(0)(Q) + D(P)(Q) <= T) {
      ans = T
    } else {
      REP(N) { i =>
        REP(N) { j =>
          // 0 -> i -> P/Q -> j -> 0
          val separeted = max(D(P)(i) + D(P)(j), D(Q)(i) + D(Q)(j))
          val t = D(0)(i) + separeted + D(0)(j)
          if (t <= T) ans = max(ans, T - separeted)
        }
      }
    }

    out.println(ans)
  }

  case class Edge(to: Int, weight: Int)
  type WUGraph = Array[Array[Edge]]
  def packWUGraph(n: Int, from: Array[Int], to: Array[Int], w: Array[Int]): WUGraph = {
    val g = new Array[Array[Edge]](n)
    val p = new Array[Int](n)
    val m = from.length
    REP(m)(i => p(from(i)) += 1)
    REP(m)(i => p(to(i)) += 1)
    REP(n)(i => g(i) = new Array(p(i)))
    REP(m) { i =>
      p(from(i)) -= 1
      g(from(i))(p(from(i))) = Edge(to(i), w(i))
      p(to(i)) -= 1
      g(to(i))(p(to(i))) = Edge(from(i), w(i))
    }
    g
  }

  case class Visit(node: Int, cost: Long) extends Comparable[Visit] {
    override def compareTo(o: Visit): Int = java.lang.Long.compare(cost, o.cost)
  }
  val queue = new java.util.PriorityQueue[Visit](1e5.toInt) // 使い回す
  def dijk(g: WUGraph, start: Int): Array[Long] = {
    val d = Array.fill[Long](g.length)(Long.MaxValue / 2)
    d(start) = 0
    queue.add(Visit(start, 0))

    while(!queue.isEmpty) {
      val v = queue.poll()
      if (d(v.node) == v.cost) {
        REP(g(v.node).length) { i =>
          val e = g(v.node)(i)
          val next = v.cost + e.weight
          if (d(e.to) > next) {
            d(e.to) = next
            queue.add(Visit(e.to, next))
          }
        }
      }
    }

    d
  }
}