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 C# (Mono 4.6.2.0) (judge verdict: Wrong Answer)

using System;

namespace kadai1._1
{
    class Program
    {
        static void Main(string[] args)
        {
                Console.WriteLine("A,Bの値を入力してください。");
                string[] array = Console.ReadLine().Split(' ');
                int a = int.Parse(array[0]);
                int b = int.Parse(array[1]);
                int sum = 0;

                if (a < 3 || b > 20)
                {
                    Console.WriteLine("エラー");
                }

                else
                {
                    for (int i = 0; i < 2; i++)
                    {
                        if (a > b)
                        {
                            sum = sum + a;
                            a--;
                        }
                        else
                        {
                            sum = sum + b;
                            b--;
                        }
                    }

                    Console.Write("コインは合計で");
                    Console.Write(sum);
                    Console.WriteLine("枚もらえます。");
                }
            }
        }
    }