import java.util.Scanner;

class Test {
	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		int W = in.nextInt();
		int D = in.nextInt();
		int temp = 0;

		for(int i=1; i<=D-1; i++) {
			temp = (int)Math.floor(W / D * D);
			W -= temp;
			D--;
		}

		System.out.println(temp);
	}
}