import java.util.Scanner;

public class BaseConverter {

    // 将任意进制数转换为十进制数  
    public static long convertToDecimal(String number, int base) {
        long decimal = 0;
        int length = number.length();

        for (int i = 0; i < length; i++) {
            char digit = number.charAt(length - 1 - i);
            int value;

            if (digit >= '0' && digit <= '9') {
                value = digit - '0';
            } else if (digit >= 'A' && digit <= 'F') {
                value = digit - 'A' + 10;
            } else if (digit >= 'a' && digit <= 'f') {
                value = digit - 'a' + 10;
            } else {
                throw new IllegalArgumentException("Invalid character in number: " + digit);
            }

            decimal += value * Math.pow(base, i);
        }

        return decimal;
    }

    // 将十进制数转换为任意进制数  
    public static String convertToBase(long decimal, int base) {
        if (base < 2 || base > 16) {
            throw new IllegalArgumentException("Base must be between 2 and 16");
        }

        StringBuilder result = new StringBuilder();
        char[] digits = "0123456789ABCDEF".toCharArray();

        while (decimal > 0) {
            int remainder = (int) (decimal % base);
            result.insert(0, digits[remainder]);
            decimal /= base;
        }

        if (result.length() == 0) {
            result.append('0');
        }

        return result.toString();
    }

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

        System.out.print("Enter the number X: ");
        String numberX = scanner.nextLine();

        System.out.print("Enter the base of X (2-16): ");
        int baseX = scanner.nextInt();

        System.out.print("Enter the desired base Y (2-16): ");
        int baseY = scanner.nextInt();

        try {
            long decimal = convertToDecimal(numberX, baseX);
            String numberY = convertToBase(decimal, baseY);

            System.out.println("The number " + numberX + " in base " + baseX + " is " + numberY + " in base " + baseY);
        } catch (Exception e) {
            System.err.println("Error: " + e.getMessage());
        }

        scanner.close();
    }
}