5 3
 1000 3
 777 17
 4 3
 2 2
 100 4
 10 4
 999 2
 6 4
 1 2
 17 3
 1 4
 26 8
 91 5
 1 3
 1000 2
 20 3
 9 4
 123 5
 1000 1000
 3 2
 3 3
 80 970
 1000 4
 1 1000

7
 1499
 825
 5
 3
 133
 13
 1997
 7
 1
 25
 1
 29
 113
 1
 1999
 29
 11
 153
 1001
 5
 4
 80
 1333
 1

import java.util.Scanner;
public class NewYearCandles {

	public static void main(String[] args) {
		Scanner in = new Scanner (System.in);
		int a = in.nextInt();
		int b = in.nextInt();

		int hours = a;
		int remA = a % b ;
		if(remA<5 &&remA !=0){
			remA =1 ;
		}
		int totA = a/b ;
		int remtotA = totA % b ;
		int bigtotA = totA/b;
		if(remtotA<5 &&remtotA !=0){
			remtotA =1 ;
		}
		hours += remA + totA + remtotA + bigtotA;
		int sum = a+b;
		if(sum % 2 !=0){
			hours--;
		}
		System.out.println(hours);
	}
}