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 Ruby (2.3.3) (judge verdict: Wrong Answer)

i = gets
n = i.length
i = i.to_i(2)

io = ""
oi = ""
n.times{|t|
    k = t%2
io += k.to_s

}
io = io.to_i(2)
oi = -~io


a = (i ^ io).to_s(2).count("1")
b = (i ^ oi).to_s(2).count("1")

if a >= b then
    puts b
else
    puts a
end