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 (GCC 5.4.1) (judge verdict: Wrong Answer)

// AtCoder124-1.cpp : コンソール アプリケーションのエントリ ポイントを定義します。
//

#include<stdio.h>


int main()
{
	int a, b, c;
	int sum = 0;
	scanf("%d", &a);
	scanf("%d", &b);
	sum=a*b;
	if (a*(a - 1) > sum) {
		 sum= a*(a - 1);
	}
	if (b*(b - 1) > sum) {
		sum= b*(b - 1);
	}
	printf("%d", sum);
    return 0;
}