## Problem E. Easy patrol ≡

 Author: A. Klenin, M. Sporyshev Time limit: 1 sec Input file: input.txt Memory limit: 256 Mb Output file: output.txt

### Statement

Young programmer Vasya tinkered with robots, and decided to create a new startup Easy Patrol with the goal of producing robot guardian to replace human guards.

As a first step, he considered a single wall of N meters in length and two patrolling robots moving back and forth along it.

First robot starts patrolling at the point located x meters from the left edge of the wall, moving to the right. Second robot starts patrolling at the point located y meters from the left edge of the wall, moving to the left.

Each second, events happen in the following order:

1. if robots are about to collide (that is, are facing each other at the distance 0 or 1 meters), both reverse direction.
2. each robot checks whether it has reached the edge and reverses direction if it is so.
3. both robots move simultaneously, each for exactly 1 meter in its current direction.

Your program must determine maximum possible distance between two robots.

### Input file format

Input file contains integers N, x, y.

### Output file format

Output file must contain a single integer — maximum distance between robots in meters.

4 ≤ N ≤ 106

0 ≤ x, y ≤ N

### Sample tests

No. Input file (input.txt) Output file (output.txt)
1
5 1 3
4

2
8 3 1
4

0.022s 0.007s 9