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();
    	if (n % d == 0) {
    	    System.out.println(n / d - 1);
    	} else {
    	    System.out.println((n % d + 1) * (n / d));
    	}
	}
}