import java.util.*;
import java.math.*;
import java.io.*;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int x = sc.nextInt();
		int y = sc.nextInt();
		int r = sc.nextInt();
		System.out.printf("%.0f\n",Math.ceil(Math.abs(x) + Math.abs(y) + Math.sqrt(2) * r));
	}
}