import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		long L,K;
		L = scan.nextInt();
		K = scan.nextInt();
		long haruka_length = K;
		long yu_length = K;
		long yu_total = 0;

		while(L >= 0){
			if(L - haruka_length - yu_length <= 0){
				L -= haruka_length;
			}else{
				yu_total += yu_length;
				L = L - haruka_length - yu_length;
			}
		}
		System.out.println(yu_total);
		scan.close();
	}
}