import java.util.Scanner;

public class Hex2Dec2 {

    public static void main(String[] args) {

        Scanner in = new Scanner(System.in);
        System.out.print("Please enter a 2-digit hex number: ");
        String hex = in.nextLine().trim();
        in.close();

        if (hex.length() != 2) {
            System.err.println("Invalid input");
            System.exit(1);
        }

        int value = 0;

        char ch = Character.toUpperCase(hex.charAt(1));
        if ('A' <= ch && ch <= 'F')
            value += ch - 'A' + 10;
        else if (Character.isDigit(ch))
            value += ch - '0';
        else {
            System.err.println("Invalid digit");
            System.exit(2);
        }

        ch = Character.toUpperCase(hex.charAt(0));
        if ('A' <= ch && ch <= 'F')
            value += (ch - 'A' + 10) * 16;
        else if (Character.isDigit(ch))
            value += (ch - '0') * 16;
        else {
            System.err.println("Invalid digit");
            System.exit(2);
        }

        System.out.printf("The value of %s is %d", hex, value);
    }

}