stdin.ReadLine() |> ignore
let eo x = if x &&& 1 = 1 then 1L else 1L <<< 32
let f x = (x>>>32)-(x&&&0xFFFFFFFFL)
stdin.ReadLine().Split(' ')
|> Seq.map (int >> eo)
|> Seq.sum
|> f |> int |> abs
|> printfn "%d"