Problem:
Score : 100 points

Problem Statement

Snuke has N integers: 1,2,\ldots,N.
He will choose K of them and give those to Takahashi.

How many ways are there to choose K consecutive integers?

Constraints

All values in input are integers.

1 \leq K \leq N \leq 50

Input

Input is given from Standard Input in the following format:

N K

Output

Print the answer.

Sample Input 1

3 2

Sample Output 1

2

There are two ways to choose two consecutive integers: (1,2) and (2,3).

Sample Input 2

13 3

Sample Output 2

11

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

(* O(n) *)
let solve n k =
  let rec find acc i =
    if i + k - 1 > n then
      acc
    else
      find (acc + 1) (i + 1)
  in
    find 0 1

let read_ints () = read_line () |> Str.split (Str.regexp " ") |> List.map int_of_string

let _ =
  match read_ints () with
  | [n; k] -> solve n k |> string_of_int |> print_endline
  | _ -> ()