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;

macro_rules! read {
    ($t: ty) => {{
        let mut line = String::new();
        stdin().read_line(&mut line);
        line.trim().parse::<$t>().unwrap()
    }};
    ($($t: ty), *) => {{
        let mut line = String::new();
        stdin().read_line(&mut line);
        let mut iter = line.split_whitespace();
        (
            $(iter.next().unwrap().parse::<$t>().unwrap(), )*
        )
    }}
}
macro_rules! reads {
    ($e:expr, $t:ty) => {{
        let mut v = vec![];
        for _ in 0..$e {
            let mut line = String::new();
            stdin().read_line(&mut line);
            v.push(line.trim().parse::<$t>().unwrap());
        }
        v
    }};
}

fn main() {
    let (mut a, mut b) = read!(u64, u64);

    let mut s = 0;

    if a > b {
        s = s + a;
        a = a - 1;
    } else {
        s = s + b;
        b = b - 1;
    }

    if a > b {
        s = s + a;
        a = a - 1;
    } else {
        s = s + b;
        b = b - 1;
    }

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