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 Rust (1.15.1) (judge verdict: Accepted)

use std::io::stdin;

fn main() {
    let mut ab = String::new();
    stdin().read_line(&mut ab).unwrap();
    let mut ab: Vec<usize> = ab.trim().split_whitespace().flat_map(str::parse).collect();
    ab.sort();
    let (a, b) = (ab[0], ab[1]);
    let c = if b - a < 2 {
        a + b
    } else {
        b + b - 1
    };
    println!("{}", c);
}