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 C (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <stdio.h>
int main()
{
  int x, y;
  int coin=0;
  do{
    printf("整数を２つ入力："); scanf("%d %d", &x, &y);
  } while(x<3 || y<3 || x>20 || y>20);

  if(x==y){
    coin=x+y;
    return 0;
  }
    for(int i=0;i<2;i++){
      if(x>y){
	coin+=x;
	x--;
      }else{
	coin+=y;
	y--;
      }
    }
  
  printf("%d\n", coin);
  
    
  return 0;
}