let R() = stdin.ReadLine()

let N = R() |> int
let A = R().Split() |> Array.map (int >> fun x -> x - 1) |> Array.sort

let ans = 
    A 
    |> Array.indexed 
    |> Array.fold (fun acc (idx,value) -> acc + abs(idx - value)) 0

ans |> printfn "%i"