package no172;

import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int x = Math.abs(sc.nextInt());
		int y = Math.abs(sc.nextInt());
		int r = sc.nextInt();
		int x2 = x + y;
		int y2 = x - y;
		System.out.println((int) Math.ceil(1E-9 + Math.max(x2,y2) + Math.sqrt(2) * r));
	}

}