import java.util.*;

public class Exercise116{
  public static void main (String[] args){

    Scanner sc = new Scanner(System.in);

    int x = Math.abs(sc.nextInt());
    int y = Math.abs(sc.nextInt());
    double r = sc.nextInt();

    double p = Math.sqrt(r * r / 2);
    int pd = 0;
    if(p - Math.floor(p) > 0.5){
      pd = (int)(Math.ceil(p) * 2);
    }else{
      pd = (int)((Math.floor(p) + 0.5) * 2);
    }
    System.out.println(x + y + pd);
  }
}