package yukicoder172;
import java.util.Scanner;
public class Main {
	public static void main(String[] args){
		double[] xx={1,-1,0,0,1.4141356/2,-1.4141356/2,1.4141356/2,-1.4141356/2};
		double[] yy={0,0,1,-1,1.4141356/2,-1.4141356/2,-1.4141356/2,1.4141356/2};
		
		Scanner sc=new Scanner(System.in);
		double x=sc.nextDouble();
		double y=sc.nextDouble();
		double r=sc.nextDouble();
		double len=0;
		for(int i=0;i<8;i++){
			len=Math.max(Math.ceil((Math.abs(0.001+x+xx[i]*r)+Math.abs(0.001+y+yy[i]*r))),len);
		}
		System.out.println((int)len);
	}
}