import java.util.Scanner;

public class Main {
    long N;
    long M;
    long Dist;
    long Digit;
    boolean endflg;
    Scanner sc = new Scanner(System.in);
    public static void main(String[] args) {
        new Main().solve();
    }

    void solve() {
        N = sc.nextLong();
        M = sc.nextLong();
        Dist = N / M;
        Dist = (Dist / 1000) * 1000;
        endflg = false;
        if(Dist < 1000) {
            System.out.println(0);
        } else {
            while(endflg) {
                if(Dist * M > N) {
                    Dist = Dist - 1000;
                } else {
                    endflg = true;
                }
            }
            System.out.println(Dist);
        }
    }
}