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)

fn get_input() -> String {
    let mut word = String::new();
    std::io::stdin().read_line(&mut word).unwrap();
    word.trim().to_owned()
}

fn main() {
    let (mut a, mut b) = {
        let line = get_input();
        let mut split = line.split_whitespace();
        let a:u64 = split.next().unwrap().parse().unwrap();
        let b:u64 = split.next().unwrap().parse().unwrap();
        (a, b)
    };

    let mut ans = 0;

    for _ in 0..2 {
        if a > b {
            ans += a;
            a -= 1;
        } else {
            ans += b;
            b -= 1;
        }
    }

    println!("{}", ans);
}