import java.util.*;
public class Ufo {
	public static void main(String[] arg){
		Scanner sc = new Scanner(System.in);
		int x,y,r,res;
		double temp;
		x = sc.nextInt();
		y = sc.nextInt();
		r = sc.nextInt();
		temp = 2 * r / Math.sqrt(2);
		res = Math.abs(x)+Math.abs(y)+(int)temp + 1;
		System.out.println(res);
	}
}