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)

input = STDIN.gets.chomp
 
cases = ['', '']
(0..input.size).each do |n|
  cases[0] << n % 2 == 0 ? '0' : '1'
end
(0..input.size).each do |n|
  cases[1] << n % 2 != 0 ? '0' : '1'
end
 
answer = []
 
cases.each_with_index do |testcase, answer_i|
  answer[answer_i] = 0
  input.chars.each_with_index do |s, i|
    answer[answer_i] += 1 if input[i] != testcase[i]
  end
end
  
puts answer.min