#include<bits/stdc++.h>
using namespace std;
int main(){
	string s;
	long long c=0,t=1;
	cin>>s;
	for(int i=s.size()-1;i>=0;i--){
		if(s[i]>'9') c=c+(s[i]+55)*t;
		else c=c+(s[i]+48)*t;
	}
	t=t*16;
	cout<<c;
	return 0;
}
/**************************************************************
	Problem: 1292
	User: zengyixuan
	Language: C++
	Result: Wrong Answer
****************************************************************/