let ``No.21 平均の差`` () =
    let N = int <| stdin.ReadLine()
    let K = int <| stdin.ReadLine()
    let s = [ for i in 1..N -> int <| stdin.ReadLine() ] |> List.sort
    printfn "%d" <| s.Head - s.[s.Length-1]
``No.21 平均の差`` ()