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 Python (3.4.3) (judge verdict: Wrong Answer)

def read_line(*types): return [f(a) for a, f in zip(input().split(), types)]

s, = read_line(str)

# print(s)

c = 0
count_start_0 = 0
for i in range(len(s)):
    if int(s[i]) == c:
        count_start_0 += 1
    c = 0 if c == 1 else 1

count_start_1 = len(s) - count_start_0

print(min([count_start_0, count_start_1]))