优雅，实在是太优雅了

import java.util.Scanner;
import java.util.HashMap;
// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int num = 0, bit = 0;
        String s = in.next().substring(2);
        int n = s.length();
        for(int i = n - 1; i >= 0; --i){
            int nu = charToNum(s.charAt(i));
            num += (nu << bit);
            bit += 4;
        }
        System.out.println(num);
    }
    public static int charToNum(char c){
        if(c >= '0' && c <= '9')return c - '0';
        if(c >= 'a' && c <= 'z')return c - 'a' + 10;
        return c - 'A' + 10;
    }
}