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 mut input = String::new();
    std::io::stdin().read_line(&mut input).unwrap();
    let mut v: Vec<u32> = input.trim().split_whitespace()
        .map(|x| x.parse().unwrap()).collect();
    let mut ans = 0;
    let mut i = 2;
    loop {
        if ( i == 0 ) {
            break;
        }
        if ( v[0] >= v[1]) {
            ans += v[0];
            v[0] -= 1;
        } else {
            ans += v[1];
            v[1] -= 1;
        }
        i -= 1;
    }
    println!("{}", ans);
}