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::Read;
use std::cmp;

fn main() {
    let mut buf = String::new();

    // 標準入力から全部bufに読み込む
    std::io::stdin().read_line(&mut buf);

    // 読み込んだStringを空白で分解する
    let mut iter = buf.split_whitespace();

    // 入力を受け取る
    let mut a: usize = iter.next().unwrap().parse().unwrap();
    let mut b: usize = iter.next().unwrap().parse().unwrap();

    // 答え
    let mut num_coins: usize = 0;

    for i in 0..2 {
        if (a > b) {
            num_coins += a;
            a -= 1;
        } else {
            num_coins += b;
            b -= 1;
        }
    }

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