某商品有2种不同数量的包装，对应不同的价格；同时提供满200元减50元的不限量购物券，试求解最好购买策略，在单次购买中以最低总价购买正好500个商品

import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int aNum = scanner.nextInt();
        int aPrice = scanner.nextInt();
        int bNum = scanner.nextInt();
        int bPrice = scanner.nextInt();
        int x = 0, y = 0, totalPrice = 0;
        for (int i = 0; i * aNum <= 500; i++) {
            if ((500 - i * aNum) % bNum == 0){
                int total = i * aPrice + (500 - i * aNum) / bNum * bPrice;
                int newTotal = total - total / 200 * 50;
                if (totalPrice == 0){
                    totalPrice = newTotal;
                    x = i;
                    y = (500 - i * aNum) / bNum;
                }else if (newTotal < totalPrice){
                    totalPrice = newTotal;
                    x = i;
                    y = (500 - i * aNum) / bNum;
                }
            }
        }
        if (x == 0 && y == 0){
            System.out.println(-1);
        }else System.out.println(x + " " + y);
    }
}