题解 | #进制转换#

import java.util.*;
public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        char[] chars = scanner.nextLine().toLowerCase().toCharArray();
        long res = 0;
        String a = "0123456789abcdef";
        for (int i = 0; i < chars.length - 2; i++) {
            res += a.indexOf(chars[chars.length - 1 - i]) * Math.pow(16, i);
        }
        System.out.println(res);
    }
}