#include<bits/stdc++.h>
using namespace std;
int main(){
string s;
cin>>s;
long long c=0,t=1;
for(int i=s.size()-1;i>=0;i--){
	if(s[i]<='A'&&s[i]<='Z'){
		c=c+(s[i]-55)*t;
	}else{
		c=c+(s[i]-'0')*t;
	}
	t=t*16;
}
cout<<c;
    return 0;
}
/**************************************************************
	Problem: 1292
	User: linyuhang
	Language: C++
	Result: Wrong Answer
****************************************************************/