#include<bits/stdc++.h>
using namespace std;
int main(){
	string n;
	int k=0,t=1;
	cin>>n;
	for(int i=n.size()-1;i>=0;i--){
		if(n[i]>='A'&&n[i]<='F'){
			k=k+int(n[i]-55)*t;
			t=t*16;
		}
		else{
			k=k+(n[i]-48)*t;
			t=t*16;
		}
	}
	cout<<k;
	return 0;
}

/**************************************************************
	Problem: 1292
	User: xuanhua
	Language: C++
	Result: Wrong Answer
****************************************************************/