import java.util.Scanner;

public class Calculator {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        System.out.print("请输入要转换的数：");
        String num = scanner.nextLine();

        System.out.print("请输入源进制(2-16)：");
        int fromBase = scanner.nextInt();

        System.out.print("请输入目标进制(2-16)：");
        int toBase = scanner.nextInt();

        // 调用转换方法
        String converted = convertBase(num, fromBase, toBase);

        System.out.printf("%s (base %d) 转换为 base %d 是 %s%n", num, fromBase, toBase, converted);
    }

    public static String convertBase(String num, int fromBase, int toBase) {
        // 将给定的fromBase进制数转换为十进制数
        int decimalNum = Integer.parseInt(num, fromBase);

        // 定义字符集以表示大于10的进制数
        char[] digits = "0123456789ABCDEF".toCharArray();

        // 如果目标进制是10，则直接返回decimalNum
        if (toBase == 10) {
            return String.valueOf(decimalNum);
        }

        // 否则，从十进制转换为目标进制
        StringBuilder result = new StringBuilder();
        while (decimalNum > 0) {
            int remainder = decimalNum % toBase;
            result.insert(0, digits[remainder]);
            decimalNum /= toBase;
        }

        return result.toString();
    }
}