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 read_vec<T: std::str::FromStr>() -> Vec<T> {
  let mut s = String::new();
  std::io::stdin().read_line(&mut s).ok();
  s.trim().split_whitespace()
    .map(|e| e.parse().ok().unwrap()).collect()
}
 
fn main() {
  let mut ab: Vec<u32> = read_vec();
  let mut ans: u32 = 0;

  for _ in 0..2 {
    if ab[0] > ab[1] {
      ans += ab[0];
      ab[0] -= 1;
    } else {
      ans += ab[1];
      ab[1] -= 1;
    }
  }

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