using System;

class Program
{
    static void Main()
    {
        var tmp = Console.ReadLine().Split();
        int a = int.Parse(tmp[0]);
        int b = int.Parse(tmp[1]);
        int s = int.Parse(tmp[2]);

        int ans = 0;

        if (Math.Abs(a - s) <= Math.Abs(b - s))
        {
            if (a < s) ans += s - a;
            ans += s;
        }
        else
        {
            if (a > b)
            {
                if (s > b) ans += 2 * a - b;
                else ans += 2 * a - s;
            }
            else
            {
                if (a == 0) ans++;
                if (s > b) ans += 2 * s - b;
                else ans += b;
            }
        }

        Console.WriteLine(ans);
    }
}