import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		double x = sc.nextDouble();
		double y = sc.nextDouble();
		y+= y+1;
		System.out.println((int)Math.ceil(x/y));

	}

} import java.util.Scanner; Scanner java.util public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		double x = sc.nextDouble();
		double y = sc.nextDouble();
		y+= y+1;
		System.out.println((int)Math.ceil(x/y));

	}

} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		double x = sc.nextDouble();
		double y = sc.nextDouble();
		y+= y+1;
		System.out.println((int)Math.ceil(x/y));

	} main {
		Scanner sc = new Scanner(System.in);
		double x = sc.nextDouble();
		double y = sc.nextDouble();
		y+= y+1;
		System.out.println((int)Math.ceil(x/y));

	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) double x = sc.nextDouble(); x sc.nextDouble() sc.nextDouble sc double y = sc.nextDouble(); y sc.nextDouble() sc.nextDouble sc y+= y+1 y y+1 y 1 System.out.println((int)Math.ceil(x/y)) System.out.println System.out System System.out (int)Math.ceil(x/y) Math.ceil Math x/y x y String[] args args public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		double x = sc.nextDouble();
		double y = sc.nextDouble();
		y+= y+1;
		System.out.println((int)Math.ceil(x/y));

	}

} public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		double x = sc.nextDouble();
		double y = sc.nextDouble();
		y+= y+1;
		System.out.println((int)Math.ceil(x/y));

	}

} Main
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		double x = sc.nextDouble();
		double y = sc.nextDouble();
		y+= y+1;
		System.out.println((int)Math.ceil(x/y));

	}

}
