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>
#include <stdlib.h>

int main(void){

  int   a[100], count, i, tmp, n, m;

  count = 0;
  while (( tmp = getchar()) != '\n' ){
    a[count] = tmp - 48;
    count++;
  }

  n = 0;
  for (size_t i = 0; i < count; i++) {
    if (( i % 2 == 0) && ( a[i] == 1 )) {
    }else if (( i % 2 != 0) && ( a[i] == 0 )) {
    }else{
      n++;
    }
  }
  m = 0;
  for (size_t i = 0; i < count; i++) {
    if (( i % 2 == 0) && ( a[i] == 0 )) {
    }else if (( i % 2 != 0) && ( a[i] == 1 )) {
    }else{
      m++;
    }
  }

  if (n < m) {
    printf("%d\n", n);
  }else{
    printf("%d\n", m);
  }

  return 0;

}