Problem:
Score : 100 points

Problem Statement

Takahashi wants to print a document with N pages double-sided, where two pages of data can be printed on one sheet of paper.

At least how many sheets of paper does he need?

Constraints

N is an integer.

1 \leq N \leq 100

Input

Input is given from Standard Input in the following format:

N

Output

Print the answer.

Sample Input 1

5

Sample Output 1

3

By printing the 1-st, 2-nd pages on the 1-st sheet, 3-rd and 4-th pages on the 2-nd sheet, and 5-th page on the 3-rd sheet, we can print all the data on 3 sheets of paper.

Sample Input 2

2

Sample Output 2

1

Sample Input 3

100

Sample Output 3

50

Solution in OCaml (4.02.3) (judge verdict: Accepted)

open Batteries
open BatPrintf

let scan fmt f =
  Scanf.sscanf (read_line ()) fmt f

let scan_list cnv =
  read_line ()
  |> String.split_on_char ' '
  |> List.map cnv

let scan_listn n cnv =
  (0 --^ n) |> Enum.map (fun _ -> (cnv % read_line) ())

let bsearch_ge arr a =
  let l = Array.length arr in
  match Array.bsearch Int.ord arr a with
  | `All_lower -> l
  | `All_bigger -> 0
  | `Just_after n -> l - n -1
  | `At n -> l - n
  | `Empty -> 0

let rec zip xs ys =
  match xs, ys with
  | [], _ -> []
  | _, [] -> []
  | x::xs, y::ys ->
    (x, y) :: zip xs ys

let square x = x * x

let dbg n = Printf.eprintf "%s\n" @@ dump n; n

let n = scan "%d" identity

let () =
  succ n / 2
  |> printf "%d"