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>
#include<string.h>
 
int main(void){
 
    char S[100000],S_sub[100000];
    int i,lenth,result = 0;
 
    scanf("%s",S);
    lenth = strlen(S);
 
    if(S[0] == '0'){
        for(i = 0;i < lenth;i++){
            if(i % 2 == 0){
                S_sub[i] = '0';
            }else{
                S_sub[i] = '1';
            }
        }
    }else{
        for(i = 0;i < lenth;i++){
            if(i % 2 == 0){
                S_sub[i] = '1';
            }else{
                S_sub[i] = '0';
            }
        }
    }
 
    for(i = 0;i < lenth;i++){
        if(S[i] != S_sub[i]){
            result++;
        }
    }
    
    printf("%d",result);
    return 0;
}