package m.shin.level1;
import java.util.Scanner;

public class No172 {

	public static void main(String[] args) {
		Scanner s = new Scanner(System.in);
		int x = Math.abs(s.nextInt()) , y = Math.abs(s.nextInt()) , r = s.nextInt();
		s.close();

		System.out.println(Math.ceil(x + y + Math.sqrt(2)*r));

	}

}