let [| n; s; t; k |] =
    stdin.ReadLine().Split()
    |> Array.map int

let arr =
    stdin.ReadLine().Split()
    |> Array.map int

let f (xs: int array) (idx: int) : int =
    let mutable result = 1e9 |> int
    for i in 0 .. xs.Length - 1 do
        if i <> idx then
            if result > xs.[i] then
                result <- xs.[i]
    result

if arr.[s - 1] + arr.[t - 1] <= k then
    1
else
    let m = f arr (s - 1)

    if m + arr.[t - 1] <= k then
        2
    else
        -1
|> printfn "%d"