package main

import . "fmt"
import . "slices"

func main() {
	var n,s,t,k int
	Scan(&n,&s,&t,&k)
	a:=make([]int,n)
	for i:=range a {
		Scan(&a[i])
	}
	m:=Min(a)
	s--
	t--
	if a[s]+a[t]<=k {
		Println(1)
	} else if a[s]+m<=k&& a[t]+m<=k  {
		Println(2)
	} else {
		Println(-1)
	}
}