using static System.Math;
using System;

public class Hello
{
    public static void Main()
    {
        string[] line = Console.ReadLine().Trim().Split(' ');
        var a = int.Parse(line[0]);
        var b = int.Parse(line[1]);
        var s = int.Parse(line[2]);
        var ans = getAns(a, b, s);
        Console.WriteLine(ans);
    }
    public static int getAns(int a, int b, int s)
    {
        if (s == 1 && a == 0) return 2;
        if (s == 1 && a > 0) return a;
        var a1 = Abs(a - s);
        var b1 = Abs(b - s);
        if (a1 <= b1) return a1 + s;
        int via1;
        if (a == 0) via1 = b1 + s - 1 + 2;
        else via1 = b1 + s - 1 + a;
        int viaa;
        if (a == 0) viaa = b1 + Abs(s - 1) + 2;
        else viaa = b1 + Abs(s - a) + a;
        return Min(via1, viaa);
    }
}