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)

#[allow(unused_imports)]
use std::cmp::{max, min, Ordering};
#[allow(unused_imports)]
use std::collections::{BTreeMap, BTreeSet, BinaryHeap, HashMap, HashSet, VecDeque};
#[allow(unused_imports)]
use std::io::prelude::BufRead;
#[allow(unused_imports)]
use std::io::{stdin, stdout, BufReader, BufWriter, Write};
#[allow(unused_imports)]
use std::mem::swap;
#[allow(unused_imports)]
use std::str::FromStr;

fn main() {
	let line = read_vector::<usize>();
	let (a, b) = (line[0], line[1]);
	let ans = if a > b { 2 * a - 1 } else if b > a { 2 * b - 1 } else { a + b };
	println!("{}", ans);
}
#[allow(dead_code)]
fn read<T>() -> T
where
    T: std::str::FromStr,
    T::Err: std::fmt::Debug,
{
    let mut buf = String::new();
    stdin().read_line(&mut buf).unwrap();
    return buf.trim().parse().unwrap();
}

#[allow(dead_code)]
fn read_vector<T>() -> Vec<T>
where
    T: std::str::FromStr,
    T::Err: std::fmt::Debug,
{
    let mut buf = String::with_capacity(100);
    stdin().read_line(&mut buf).unwrap();
    return buf.split_whitespace().map(|s| s.parse().unwrap()).collect();
}

#[allow(dead_code)]
fn read_matrix<T>() -> Vec<Vec<T>>
where
    T: std::str::FromStr,
    T::Err: std::fmt::Debug,
{
    use std::io::prelude::*;
    let stdin = stdin();
    let mut reader = BufReader::with_capacity(100 * 1024, stdin);
    let mut line = String::with_capacity(100);
    let mut matrix: Vec<Vec<T>> = Vec::new();

    while reader.read_line(&mut line).unwrap() > 0 {
        matrix.push(
            line.trim()
                .split_whitespace()
                .map(|s| s.parse().unwrap())
                .collect(),
        );
        line.clear();
    }

    return matrix;
}

#[allow(dead_code)]
fn read_chars() -> Vec<char> {
    let stdin = stdin();
    let mut buf = String::new();
    let _bytes = stdin.read_line(&mut buf).unwrap();
    return buf.trim().chars().collect();
}