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 main() {
    let stdin = std::io::stdin();
    let mut buf = String::new();
    let _ = stdin.read_line(&mut buf);
    let ns = buf
        .split_whitespace()
        .map(|s| s.parse().unwrap())
        .collect::<Vec<isize>>();
    let (a, b) = (ns[0], ns[1]);
    if a < b {
        println!("{}", b * 2 - 1);
    } else if b < a {
        println!("{}", a * 2 - 1);
    } else {
        println!("{}", a * 2);
    }
}