12562: Even Odds

Being a nonconformist, Volodya is displeased with the current state of things, particularly with the order of natural numbers (natural number is positive integer number). He is determined to rearrange them. But there are too many natural numbers, so Volodya decided to start with the first n. He writes down the following sequence of numbers: firstly all odd integers from 1 to n (in ascending order), then all even

integers from 1 to n (also in ascending order). Help our hero to find out which number will stand at the position number k.

 

Input

The only line of input contains integers n and k (1≤k≤n≤1e14).  

Output

Print the number that will stand at the position number k after Volodya's manipulations.  

 

Sample test(s) input
10 3

77

output

5

6

Note

In the first sample Volodya's sequence will look like this: {1, 3, 5, 7, 9, 2, 4, 6, 8, 10}. The third place in the sequence is therefore occupied by the number 5.

Hint

注意数据的类型

use __int64 to read data and use %I64d to output data