#进制转换#__huawei_no.4-1

#include <algorithm>
#include <iostream>
#include <string>
#include <cmath>
using namespace std;

int main() {
    string str;
    getline(cin, str);
    string str2 = str.substr(2);
    reverse(str2.begin(), str2.end());
    int n = str2.size();
    int ans = 0;
    int num = 0;
    for (int i = 0 ; i < n; i++) {
        if (str2[i] >= 'A' && str2[i] <= 'F' ) {
            num = 10 + (str2[i] - 'A');
        } else if (str2[i] >= 'a' && str2[i] <= 'f' ) {
            num = 10 + (str2[i] - 'a');
        } else {
            num = str2[i] - '0';
        }
        ans += num * pow(16, i);
    }
    cout << ans << endl;
}
// 64 位输出请用 printf("%lld")

简单粗暴的方法，不能跟大佬比