using System;
using System.Collections.Generic;
using System.Linq;
using System.Numerics;
using static System.Math;

namespace SortItems
{
    class Program
    {
        static void Main(string[] args)
        {
            var n = Console.ReadLine().Split().Select(int.Parse).ToArray();
            var a = n[0];
            var b = n[1];

            if (a < b)
            {
                Console.WriteLine(b - 2);
            }
            else
            {
                Console.WriteLine(2000000000 - b - 1);
            }

        }
    }
}