using System;
using System.Linq;

class Program
{
    static void Main()
    {
        var s = Console.ReadLine().Split();
        int x = int.Parse(s[0]);
        int y = int.Parse(s[1]);
        int r = int.Parse(s[2]);

        Console.WriteLine(Math.Ceiling(Math.Abs(x) + Math.Abs(y) + Math.Sqrt(2) * r));
    }
}