Here is the code:
import java.util.Scanner;


public class Main {

    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        String s = scan.nextLine();
        String str[] = s.split(" ");

        int n = Integer.parseInt(str[0]),
            k = Integer.parseInt(str[1]);
        double res;

        res = (double) (2*n)%k;
        res /= k;
        if (res < 0.5){
                n = 2*n/k;
            }
            else{
                n = (2*n/k)+1;}

        System.out.println(Integer.toString(n));


    }

}

=========================Test

3 2 (3)
4 3 (3)
7 3 (5)