open Scanf ;;
open Printf ;;

let input_int () = scanf " %d" (fun x -> x) ;;
let input_ints n = Array.init n (fun _ -> input_int ()) ;;

let () =
  let n = input_int () in
  let b = input_ints n in
  let rec loop i s ans =
    if i = n then ans
    else begin
      let s' = s + b.(i) in
      let ans' = ans + abs (i - s) in
      loop (i + 1) s' ans'
    end
  in
  printf "%d\n" (loop 0 0 0)
  ;;