Processing math: 100%

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.

Constraints

4N106

0x,yN

Sample tests

No. Input file (input.txt) Output file (output.txt)
1
5 1 3
4
2
8 3 1
4

0.057s 0.009s 13