Problem:
Score : 100 points

Problem Statement

There are two buttons, one of size A and one of size B.

When you press a button of size X, you get X coins and the size of that button decreases by 1.

You will press a button twice. Here, you can press the same button twice, or press both buttons once.

At most how many coins can you get?

Constraints

All values in input are integers.

3 \leq A, B \leq 20

Input

Input is given from Standard Input in the following format:

A B

Output

Print the maximum number of coins you can get.

Sample Input 1

5 3

Sample Output 1

9

You can get 5 + 4 = 9 coins by pressing the button of size 5 twice, and this is the maximum result.

Sample Input 2

3 4

Sample Output 2

7

Sample Input 3

6 6

Sample Output 3

12

Solution in Common Lisp (SBCL 1.1.14) (judge verdict: Accepted)

; ABC124-A
(defun max2(a b)
  (if (> a b) a b)
  )

(defun solve(a b)
  (setq r1 (max2 a b))
  (setq r2 (if (> a b) (max2 (- a 1) b) (max2 a (- b 1))))
  (+ r1 r2)
  )

(let ((a (read)) (b (read)))
  (format t "~d~%" (solve a b))
  )