#include<bits/stdc++.h>
using namespace std;
int main(){
    string n;
    cin>>n;
    long long cnt=0;
    long long k=1;
    for(int i= n.size()-1;i>=0;i--){
        switch(n[i]){
            case '0':
            case '1':
            case '2':
            case '3':
            case '4':
            case '5':
            case '6':
            case '7':
            case '8':
            case '9':
                cnt+=(n[i]-48)*k;
                break;
                
            case 'A':
                cnt+=10*k;
                break;
            case 'B':
                cnt+=11*k;
                break;
            case 'C':
                cnt+=12*k;
                break;
            case 'D':
                cnt+=13*k;
                break;
            case 'E':
                cnt+=14*k;
                break;
            case 'F':
                cnt+=15*k;
                break;
        }
        k*=16;
    }
    cout<<cnt;
    return 0;
}
/**************************************************************
	Problem: 1292
	User: luyanchen
	Language: C++
	Result: Accepted
	Time:10 ms
	Memory:2076 kb
****************************************************************/