#include<bits/stdc++.h>
using namespace std;
int main(){
    string s;
    long long k=1,s1=0;
    cin>>s;
    for(int i=s.size()-1;i>=0;i--){
        if(s[i]>='A'&&s[i]<='F') s[i]-=55;
        else s[i]-=48;
        s1+=k*s[i];
        k*=16;
    }
    cout<<s1<<endl;
}
/**************************************************************
	Problem: 1292
	User: fzy001
	Language: C++
	Result: Accepted
	Time:12 ms
	Memory:2076 kb
****************************************************************/