import java.util.*;
public class Main{
  public static void main(String[]args){
      Scanner sc = new Scanner(System.in);

      int n = sc.nextInt();
      int d = sc.nextInt();
      int target =0;

      if(n<d){
        System.out.println(1);
        System.exit(0);
      }

      for (int i = 1;i<=n ;i++ ) {
        if(i-d==1){
          target = i+d;
        }
      }
      if(n%target!=0){
        System.out.println(n/target+1);
      }else{
        System.out.println(n/target);
      }

  }
} import java.util.*; util.* java public class Main{
  public static void main(String[]args){
      Scanner sc = new Scanner(System.in);

      int n = sc.nextInt();
      int d = sc.nextInt();
      int target =0;

      if(n<d){
        System.out.println(1);
        System.exit(0);
      }

      for (int i = 1;i<=n ;i++ ) {
        if(i-d==1){
          target = i+d;
        }
      }
      if(n%target!=0){
        System.out.println(n/target+1);
      }else{
        System.out.println(n/target);
      }

  }
} Main public static void main(String[]args){
      Scanner sc = new Scanner(System.in);

      int n = sc.nextInt();
      int d = sc.nextInt();
      int target =0;

      if(n<d){
        System.out.println(1);
        System.exit(0);
      }

      for (int i = 1;i<=n ;i++ ) {
        if(i-d==1){
          target = i+d;
        }
      }
      if(n%target!=0){
        System.out.println(n/target+1);
      }else{
        System.out.println(n/target);
      }

  } main {
      Scanner sc = new Scanner(System.in);

      int n = sc.nextInt();
      int d = sc.nextInt();
      int target =0;

      if(n<d){
        System.out.println(1);
        System.exit(0);
      }

      for (int i = 1;i<=n ;i++ ) {
        if(i-d==1){
          target = i+d;
        }
      }
      if(n%target!=0){
        System.out.println(n/target+1);
      }else{
        System.out.println(n/target);
      }

  } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc int d = sc.nextInt(); d sc.nextInt() sc.nextInt sc int target =0; target 0 if(n<d){
        System.out.println(1);
        System.exit(0);
      } n<d n d {
        System.out.println(1);
        System.exit(0);
      } System.out.println(1) System.out.println System.out System System.out 1 System.exit(0) System.exit System 0 for (int i = 1;i<=n ;i++ ) {
        if(i-d==1){
          target = i+d;
        }
      } int i = 1; int i = 1; i 1 i<=n i n i++ i++ i {
        if(i-d==1){
          target = i+d;
        }
      } {
        if(i-d==1){
          target = i+d;
        }
      } if(i-d==1){
          target = i+d;
        } i-d==1 i-d i d 1 {
          target = i+d;
        } target = i+d target i+d i d if(n%target!=0){
        System.out.println(n/target+1);
      }else{
        System.out.println(n/target);
      } n%target!=0 n%target n target 0 {
        System.out.println(n/target+1);
      } System.out.println(n/target+1) System.out.println System.out System System.out n/target+1 n/target n target 1 {
        System.out.println(n/target);
      } System.out.println(n/target) System.out.println System.out System System.out n/target n target String[]args args public class Main{
  public static void main(String[]args){
      Scanner sc = new Scanner(System.in);

      int n = sc.nextInt();
      int d = sc.nextInt();
      int target =0;

      if(n<d){
        System.out.println(1);
        System.exit(0);
      }

      for (int i = 1;i<=n ;i++ ) {
        if(i-d==1){
          target = i+d;
        }
      }
      if(n%target!=0){
        System.out.println(n/target+1);
      }else{
        System.out.println(n/target);
      }

  }
} public class Main{
  public static void main(String[]args){
      Scanner sc = new Scanner(System.in);

      int n = sc.nextInt();
      int d = sc.nextInt();
      int target =0;

      if(n<d){
        System.out.println(1);
        System.exit(0);
      }

      for (int i = 1;i<=n ;i++ ) {
        if(i-d==1){
          target = i+d;
        }
      }
      if(n%target!=0){
        System.out.println(n/target+1);
      }else{
        System.out.println(n/target);
      }

  }
} Main
import java.util.*;
public class Main{
  public static void main(String[]args){
      Scanner sc = new Scanner(System.in);

      int n = sc.nextInt();
      int d = sc.nextInt();
      int target =0;

      if(n<d){
        System.out.println(1);
        System.exit(0);
      }

      for (int i = 1;i<=n ;i++ ) {
        if(i-d==1){
          target = i+d;
        }
      }
      if(n%target!=0){
        System.out.println(n/target+1);
      }else{
        System.out.println(n/target);
      }

  }
}
