# Challenges

Problem Statement

All numbers in NumberLand are standing in a circle for a dancing ceremony. Every number needs a dancing partner. Dancing partner of any number is the number which is standing radially opposite to it in the circle. The numbers are from 0 to N-1. A certain number X wants to know who will be its dancing partner. Please help X.

Input

Two positive integers denoting the value of N and X.

Output

Print the number radially opposite to X in a circle of N numbers.

Constraints

4 ≤ N ≤ 20
0 ≤ X < N

Sample Input

8 2

Sample Output

6

Dcoded By: Mrudul Sankhere

Solved By: 2936

Maximum Marks: 6