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)

class Array

  # 配列どうしの「差分」を求めるメソッド。
  # [1,2,2,3].diff([2,3,4]) => [1,2] 
  def diff(ary)
    temp = self.dup # selfの破壊を防ぐため。
    ary.each do |val|
      idx = temp.index(val)
      next if idx == nil # ary2の要素がary1にないときはパス。
      temp.delete_at(idx)
     end
     temp
  end

end
zs = (1..50000).to_a.fill(0).zip((1..50000).to_a.fill(1)).join("").split("").map(&:to_i)
os = (1..50000).to_a.fill(1).zip((1..50000).to_a.fill(0)).join("").split("").map(&:to_i)
s = gets.chomp.split("").map(&:to_i)
i = 0
zssabun = 0
ossabun = 0
while i<10
  if zs.take(s.size)[i] != s[i]
    zssabun+=1
  end
  i+=1
end
i = 0
while i<10
  if os.take(s.size)[i] != s[i]
    ossabun+=1
  end
  i+=1
end
puts [zssabun,ossabun].sort[0]