//x的初始值一定要設置為0,否則測試的答案是對的,但是通不過去

#include<bits/stdc++.h>

using?namespace?std;

const?int?N=50;

int?a[N];

using?ll=long?long;

int?main(){

??ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);

??string?s="2021ABCD";

??for(int?i=0;i<s.length();i++){

????if(s[i]>='0'&&s[i]<='9'){

??????a[i+1]=s[i]-'0';

????}

????else{

??????a[i+1]=s[i]-'A'+10;

????}

??}

??

??ll?x=0;

??for(int?i=1;i<=s.length();i++){

????x=x*16+a[i];

??}

??cout<<x<<endl;

??

??return?0;

}