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 Fortran (GNU Fortran 9.2.1) (judge verdict: Wrong Answer)

program answer
  implicit none

  integer :: N, i, count, sum
  character(len=100000) :: S, p, q

  read(*,*) S

  N = len_trim(S)
  count = 0


  do i = 1, N, 2
     p(i:i) = '0'
     q(i:i) = '1'
  end do

  do i = 2, N, 2
     p(i:i) = '1'
     q(i:i) = '0'
  end do
 do i = 1, N
     if(S(i:i)/=p(i:i)) then
        count = count + 1
     end if
  end do

  sum = 0
  do i = 1, N
     if(S(i:i)/=q(i:i)) then
        sum = sum + 1
     end if
  end do

  if(count>=sum) then
     write(*,*) sum
  else
     write(*,*) count
  end if

  stop
 end program answer